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共用题干
New Understanding of Natural Silk's Mysteries
Natural silk,as we all know,has a strength that man-made materials have long struggled to match.In a
discovery that sounds more like an ancient Chinese proverb than a materials science breakthrough,MIT re-
searchers have discovered that silk gets its strength from its weakness.Or,more specifically,its many weak-
nesses. Silk gets its extraordinary durability and ductility（柔韧性）from an unusual arrangement of hydrogen
bonds that are intrinsically very weak but that work together to create a strong,flexible structure.
Most materials一especially the ones we engineer for strength一get their toughness from brittleness.As
such,natural silks like those produced by spiders have long fascinated both biologists and engineers because of
their light weight,ductility and high strength(pound for pound,silk is stronger than steel and far less brittle).
But on its face,it doesn't seem that silks should be as strong as they are;molecularly,they are held together by
hydrogen bonds , which are far weaker than the covalent（共价的）bonds found in other molecules.
To get a better understanding of how silk manages to produce such strength through such weak bonds,
the MIT team created a set of computer models that allowed them to observe the way silk behaves at the
atomic level. They found that the arrangement of the tiny silk nanocrystals（纳米晶体）is such that the hydro-
gen bonds are able to work cooperatively,reinforcing one another against external forces and failing slowly
when they do fail,so as not to allow a sudden fracture to spread across a silk structure.
The result is natural silks that can stretch and bend while retaining a high degree of strength.But while
that's all well and good for spiders,bees and the like,this understanding of silk geometry could lead to new
materials that are stronger and more ductile than those we can currently manufacture.Our best and strongest
materials are generally expensive and difficult to produce(requiring high temperature treatments or
energy-intensive processes).
By looking to silk as a model,researchers could potentially devise new manufacturing methods that rely
on inexpensive materials and weak bonds to create less rigid,more forgiving materials that are nonetheless
stronger than anything currently on offer. And if you thought you were going to get out of this materials
science story without hearing about carbon nanotubes（纳米碳管）, think again. The MIT team is already in
the lab looking into ways of synthesizing silk-like structures out of materials that are stronger than natural
silk-like carbon nanotubes. Super-silks are on the horizon.
New Understanding of Natural Silk's Mysteries
Natural silk,as we all know,has a strength that man-made materials have long struggled to match.In a
discovery that sounds more like an ancient Chinese proverb than a materials science breakthrough,MIT re-
searchers have discovered that silk gets its strength from its weakness.Or,more specifically,its many weak-
nesses. Silk gets its extraordinary durability and ductility（柔韧性）from an unusual arrangement of hydrogen
bonds that are intrinsically very weak but that work together to create a strong,flexible structure.
Most materials一especially the ones we engineer for strength一get their toughness from brittleness.As
such,natural silks like those produced by spiders have long fascinated both biologists and engineers because of
their light weight,ductility and high strength(pound for pound,silk is stronger than steel and far less brittle).
But on its face,it doesn't seem that silks should be as strong as they are;molecularly,they are held together by
hydrogen bonds , which are far weaker than the covalent（共价的）bonds found in other molecules.
To get a better understanding of how silk manages to produce such strength through such weak bonds,
the MIT team created a set of computer models that allowed them to observe the way silk behaves at the
atomic level. They found that the arrangement of the tiny silk nanocrystals（纳米晶体）is such that the hydro-
gen bonds are able to work cooperatively,reinforcing one another against external forces and failing slowly
when they do fail,so as not to allow a sudden fracture to spread across a silk structure.
The result is natural silks that can stretch and bend while retaining a high degree of strength.But while
that's all well and good for spiders,bees and the like,this understanding of silk geometry could lead to new
materials that are stronger and more ductile than those we can currently manufacture.Our best and strongest
materials are generally expensive and difficult to produce(requiring high temperature treatments or
energy-intensive processes).
By looking to silk as a model,researchers could potentially devise new manufacturing methods that rely
on inexpensive materials and weak bonds to create less rigid,more forgiving materials that are nonetheless
stronger than anything currently on offer. And if you thought you were going to get out of this materials
science story without hearing about carbon nanotubes（纳米碳管）, think again. The MIT team is already in
the lab looking into ways of synthesizing silk-like structures out of materials that are stronger than natural
silk-like carbon nanotubes. Super-silks are on the horizon.
Biologists and engineers are interested in understanding natural silks because they are very light and brittle.
A:Right
B:Wrong
C:Not mentioned
A:Right
B:Wrong
C:Not mentioned
参考答案
参考解析
解析：题干的相关内容在第一段第二句，但文中说的是“In a discovery that sounds more like an ancient Chinese proverb than a materials science breakthrough,MIT researchers have discovered that silk gets its strength from its weakness.（一项研究的成果听起来更像一则古代中国谚语而不是材 料科学的突破，在这项研究中，麻省理工学院的研究人员发现，蚕丝的强度源于其脆弱。）”题 干说的是：麻省理工学院的研究员开展这项研究以说明一则古代中国谚语。这与文章所述不 一致。
题干的相关内容在第一段最后一句“Silk gets its extraordinary durability and ductility from an unusual arrangement of hydrogen bonds that are inherently very weak but that work together to create a strong , flexible structure.（蚕丝的异常耐久性和延展性来自一种特别的氢键结构，这些 氢键本质上非常脆弱，但它们共同创造了一种强劲而富有弹性的结构。）”题干说的是：蚕丝的 强韧来自其脆弱的氢键的协同合作。这与文章所述一致。
题干的相关内容在第二段第二句“...natural silks like those produced by spiders have long fascinated both biologists and engineers because of their light weight,ductility and high strength… （……和蜘蛛制造的蛛丝类似的天然蚕丝，因其重量轻，延展性强和韧性高，长期以来令生物学 家和工程师很感兴趣……）”题干说的是：生物学家和工程师对理解天然蚕丝很感兴趣，因为 它们很轻、很脆。这与文章所述不一致。brittle的意思是“脆的，硬但易碎的”。
题干的相关内容在第三段最后一句“...the hydrogen bonds are able to work cooperatively, reinforcing one another against external forces and failing slowly when they do fail,so as not to allowa sudden fracture to spread across a silk structure.（氢键能够齐心协力地合作，相互增援，对抗外 力，同时，它们确实维持不下去时也是慢慢衰退，这样蚕丝的整体结构就不至于出现突然的断 裂。）”题干所说的是：如果氢键因外力而断裂，它们断得很快。这与文章所述不一致。
题干所说的是：麻省理工学院研究组在研究天然蚕丝之前研究过不同的材料。这在文 中没有提及。
题干所说的是：纳米碳管是目前材料学中最盛行的话题。这在文中没有提及。
根据最后一段最后两句可知，研究人员正在想办法用比自然丝状纳米碳管更强韧的材 料合成丝状结构，超级丝就要出现了。题干所说的是：研究表明，比天然蚕丝更强韧的材料有 望在将来出现。这与文章所述一致。第3部分：概括大意与完成句子
题干的相关内容在第一段最后一句“Silk gets its extraordinary durability and ductility from an unusual arrangement of hydrogen bonds that are inherently very weak but that work together to create a strong , flexible structure.（蚕丝的异常耐久性和延展性来自一种特别的氢键结构，这些 氢键本质上非常脆弱，但它们共同创造了一种强劲而富有弹性的结构。）”题干说的是：蚕丝的 强韧来自其脆弱的氢键的协同合作。这与文章所述一致。
题干的相关内容在第二段第二句“...natural silks like those produced by spiders have long fascinated both biologists and engineers because of their light weight,ductility and high strength… （……和蜘蛛制造的蛛丝类似的天然蚕丝，因其重量轻，延展性强和韧性高，长期以来令生物学 家和工程师很感兴趣……）”题干说的是：生物学家和工程师对理解天然蚕丝很感兴趣，因为 它们很轻、很脆。这与文章所述不一致。brittle的意思是“脆的，硬但易碎的”。
题干的相关内容在第三段最后一句“...the hydrogen bonds are able to work cooperatively, reinforcing one another against external forces and failing slowly when they do fail,so as not to allowa sudden fracture to spread across a silk structure.（氢键能够齐心协力地合作，相互增援，对抗外 力，同时，它们确实维持不下去时也是慢慢衰退，这样蚕丝的整体结构就不至于出现突然的断 裂。）”题干所说的是：如果氢键因外力而断裂，它们断得很快。这与文章所述不一致。
题干所说的是：麻省理工学院研究组在研究天然蚕丝之前研究过不同的材料。这在文 中没有提及。
题干所说的是：纳米碳管是目前材料学中最盛行的话题。这在文中没有提及。
根据最后一段最后两句可知，研究人员正在想办法用比自然丝状纳米碳管更强韧的材 料合成丝状结构，超级丝就要出现了。题干所说的是：研究表明，比天然蚕丝更强韧的材料有 望在将来出现。这与文章所述一致。第3部分：概括大意与完成句子
更多 “共用题干 New Understanding of Natural Silk's MysteriesNatural silk,as we all know,has a strength that man-made materials have long struggled to match.In a discovery that sounds more like an ancient Chinese proverb than a materials science breakthrough,MIT re- searchers have discovered that silk gets its strength from its weakness.Or,more specifically,its many weak- nesses. Silk gets its extraordinary durability and ductility（柔韧性）from an unusual arrangement of hydrogen bonds that are intrinsically very weak but that work together to create a strong,flexible structure.Most materials一especially the ones we engineer for strength一get their toughness from brittleness.As such,natural silks like those produced by spiders have long fascinated both biologists and engineers because of their light weight,ductility and high strength(pound for pound,silk is stronger than steel and far less brittle). But on its face,it doesn't seem that silks should be as strong as they are;molecularly,they are held together by hydrogen bonds , which are far weaker than the covalent（共价的）bonds found in other molecules.To get a better understanding of how silk manages to produce such strength through such weak bonds, the MIT team created a set of computer models that allowed them to observe the way silk behaves at the atomic level. They found that the arrangement of the tiny silk nanocrystals（纳米晶体）is such that the hydro- gen bonds are able to work cooperatively,reinforcing one another against external forces and failing slowlywhen they do fail,so as not to allow a sudden fracture to spread across a silk structure.The result is natural silks that can stretch and bend while retaining a high degree of strength.But while that's all well and good for spiders,bees and the like,this understanding of silk geometry could lead to new materials that are stronger and more ductile than those we can currently manufacture.Our best and strongest materials are generally expensive and difficult to produce(requiring high temperature treatments or energy-intensive processes).By looking to silk as a model,researchers could potentially devise new manufacturing methods that rely on inexpensive materials and weak bonds to create less rigid,more forgiving materials that are nonetheless stronger than anything currently on offer. And if you thought you were going to get out of this materials science story without hearing about carbon nanotubes（纳米碳管）, think again. The MIT team is already in the lab looking into ways of synthesizing silk-like structures out of materials that are stronger than natural silk-like carbon nanotubes. Super-silks are on the horizon.Biologists and engineers are interested in understanding natural silks because they are very light and brittle.A:RightB:WrongC:Not mentioned ” 相关考题
考题
ENew archaeological discovers suggest that trade between Europe and Asia along the Silk Road probably began in some form. many countries earlier than once thought. The findings, coupled with a widening range of scientific and historical research could add a fascinating new page to the epic of the Silk Road.The farest and most surprising discovery is pieces of silk found in the hair of and Egyptian mummy from about 1000 BC, long before regular traffic on the Silk Road and at least one thousand years before silk was previously thought to be used in Egypt. Other research may extend human activity along this route back even further, perhaps a million years to the migration of human ancestors into eastern Asia.The official origin of East-West commerce along the road is usually placed in the late 2nd century BC which was the agent of the Chinese Emperor Wu-di returned from a dangerous secret mission（使命）across the desert into the remote high country of Central Asia. The agent, Zhang Qian, travelled as far as Afghanistan back knowledge of even more distant lands such as Persia, Syria and a place known as Lijion,. Histerents have called this one of the most important journeys in ancient times. His journey opened the way for what have been thought to be the first indirect contacts between the ancient world’s two superpowers, China and Rome. Chinese silk, first traded to central Asian tribes for war horses and to the Parthians of old Pet la lu exchange for acrobats and ostrich eggs, was soon finding its way through a network of merchants to the luxury markets in Rome.But the new discoveries show that Chinese silk was apparently present in the West long before the Han emperor started organized trade over the Silk Road. The research could change thinking about the early history of world trade and provide insights into the mystery of just how and when Europe and the Mediterranean lands first became aware of the glorious culture at the other end of Eurasia.72. The word “coupled” in the first paragraph could best be replaced by .A. producedB. contributedC. doubledD. combined
考题
The silk thread found in the hair of an Egyptian mummy suggests that .A. Egyptians had probably travelled to China to buy silkB. trade along the Silk Road began earlier than once thoughtC. historical research often achieves fascinating resultsD. new light can now be thrown on ancient trading practices
考题
Silk( )by Chinese for thousands of years now.A. has usedB. has been usedC. was usedD. is used
考题
From the passage we can conclude that______.A. different people have different ideas about the same thingB. Westerners culture is similar to our Chinese cultureC. in general, Westerners and the Chinese don't like pigsD. all of the Chinese like pigs better than Westerners
考题
The engine has more than 300（ ）,made of a number of different materials.A.compositions
B.ingredients
C.compounds
D.components
考题
共用题干
Natural MedicinesSince earliest days,humans have used some kinds of medicines.We know this because hu-mans have survived .Ancient treatments for injury and disease were successful enough to keep hu-mans from dying out completely.They were successful long before the time of modern medicine.Before the time of doctors with white coats and shiny（发亮的）instruments. Before the time of big hospitals with strange and wonderful equipment.Many parts of the world still do not have university-educated doctors.Nor do they have ex- pensive hospitals.Yet injuries are treated.And diseases are often cured.How?By ancient meth- ods. By medicines that might seem mysterious, even magical（有魔力的）.Traditional medicines are neither mysterious nor magical,however.Through the centuries, tribal（部落的）medicine men experimented with plants. They found many useful chemicals in the plants.And scientists believe many of these traditional medicines may provide the cure for some of today's most serious diseases.Experts say almost 80%of the people in the world use plants for health care.These natural medicines are used not just because people have no other form of treatment.They are used be-cause people trust them.In developed areas,few people think about the source of the medicines they buy in a store.Yet many widely-used medicines are from ancient sources,especially plants. Some experts say more than 25%of modern medicines come,in one way or another,from nature.Scientists have long known that nature is really a chemical factory.All living things contain chemicals that help them survive .So scientists' interest in traditional medicine is not new.But it has become an urgent concern.This is because the earth's supply of natural medicines may be dropping rapidly. The passage indicates that ancient treatments for injury and disease were_____.A: much more successful than modern onesB: successful enough for humans to surviveC: successful in all casesD: of little help to humans
考题
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New Understanding of Natural Silk's MysteriesNatural silk,as we all know,has a strength that man-made materials have long struggled to match.In a discovery that sounds more like an ancient Chinese proverb than a materials science breakthrough,MIT re- searchers have discovered that silk gets its strength from its weakness.Or,more specifically,its many weak- nesses. Silk gets its extraordinary durability and ductility（柔韧性）from an unusual arrangement of hydrogen bonds that are intrinsically very weak but that work together to create a strong,flexible structure.Most materials一especially the ones we engineer for strength一get their toughness from brittleness.As such,natural silks like those produced by spiders have long fascinated both biologists and engineers because of their light weight,ductility and high strength(pound for pound,silk is stronger than steel and far less brittle). But on its face,it doesn't seem that silks should be as strong as they are;molecularly,they are held together by hydrogen bonds , which are far weaker than the covalent（共价的）bonds found in other molecules.To get a better understanding of how silk manages to produce such strength through such weak bonds, the MIT team created a set of computer models that allowed them to observe the way silk behaves at the atomic level. They found that the arrangement of the tiny silk nanocrystals（纳米晶体）is such that the hydro- gen bonds are able to work cooperatively,reinforcing one another against external forces and failing slowlywhen they do fail,so as not to allow a sudden fracture to spread across a silk structure.The result is natural silks that can stretch and bend while retaining a high degree of strength.But while that's all well and good for spiders,bees and the like,this understanding of silk geometry could lead to new materials that are stronger and more ductile than those we can currently manufacture.Our best and strongest materials are generally expensive and difficult to produce(requiring high temperature treatments or energy-intensive processes).By looking to silk as a model,researchers could potentially devise new manufacturing methods that rely on inexpensive materials and weak bonds to create less rigid,more forgiving materials that are nonetheless stronger than anything currently on offer. And if you thought you were going to get out of this materials science story without hearing about carbon nanotubes（纳米碳管）, think again. The MIT team is already in the lab looking into ways of synthesizing silk-like structures out of materials that are stronger than natural silk-like carbon nanotubes. Super-silks are on the horizon.If the hydrogen bonds break due to external forces,they break fast.A:RightB:WrongC:Not mentioned
考题
共用题干
New Understanding of Natural Silk's MysteriesNatural silk,as we all know,has a strength that man-made materials have long struggled to match.In a discovery that sounds more like an ancient Chinese proverb than a materials science breakthrough,MIT re- searchers have discovered that silk gets its strength from its weakness.Or,more specifically,its many weak- nesses. Silk gets its extraordinary durability and ductility（柔韧性）from an unusual arrangement of hydrogen bonds that are intrinsically very weak but that work together to create a strong,flexible structure.Most materials一especially the ones we engineer for strength一get their toughness from brittleness.As such,natural silks like those produced by spiders have long fascinated both biologists and engineers because of their light weight,ductility and high strength(pound for pound,silk is stronger than steel and far less brittle). But on its face,it doesn't seem that silks should be as strong as they are;molecularly,they are held together by hydrogen bonds , which are far weaker than the covalent（共价的）bonds found in other molecules.To get a better understanding of how silk manages to produce such strength through such weak bonds, the MIT team created a set of computer models that allowed them to observe the way silk behaves at the atomic level. They found that the arrangement of the tiny silk nanocrystals（纳米晶体）is such that the hydro- gen bonds are able to work cooperatively,reinforcing one another against external forces and failing slowlywhen they do fail,so as not to allow a sudden fracture to spread across a silk structure.The result is natural silks that can stretch and bend while retaining a high degree of strength.But while that's all well and good for spiders,bees and the like,this understanding of silk geometry could lead to new materials that are stronger and more ductile than those we can currently manufacture.Our best and strongest materials are generally expensive and difficult to produce(requiring high temperature treatments or energy-intensive processes).By looking to silk as a model,researchers could potentially devise new manufacturing methods that rely on inexpensive materials and weak bonds to create less rigid,more forgiving materials that are nonetheless stronger than anything currently on offer. And if you thought you were going to get out of this materials science story without hearing about carbon nanotubes（纳米碳管）, think again. The MIT team is already in the lab looking into ways of synthesizing silk-like structures out of materials that are stronger than natural silk-like carbon nanotubes. Super-silks are on the horizon.It is indicated that materials stronger than natural silk can be expected in the future.A:RightB:WrongC:Not mentioned
考题
共用题干
New Understanding of Natural Silk's MysteriesNatural silk,as we all know,has a strength that man-made materials have long struggled to match.In a discovery that sounds more like an ancient Chinese proverb than a materials science breakthrough,MIT re- searchers have discovered that silk gets its strength from its weakness.Or,more specifically,its many weak- nesses. Silk gets its extraordinary durability and ductility（柔韧性）from an unusual arrangement of hydrogen bonds that are intrinsically very weak but that work together to create a strong,flexible structure.Most materials一especially the ones we engineer for strength一get their toughness from brittleness.As such,natural silks like those produced by spiders have long fascinated both biologists and engineers because of their light weight,ductility and high strength(pound for pound,silk is stronger than steel and far less brittle). But on its face,it doesn't seem that silks should be as strong as they are;molecularly,they are held together by hydrogen bonds , which are far weaker than the covalent（共价的）bonds found in other molecules.To get a better understanding of how silk manages to produce such strength through such weak bonds, the MIT team created a set of computer models that allowed them to observe the way silk behaves at the atomic level. They found that the arrangement of the tiny silk nanocrystals（纳米晶体）is such that the hydro- gen bonds are able to work cooperatively,reinforcing one another against external forces and failing slowlywhen they do fail,so as not to allow a sudden fracture to spread across a silk structure.The result is natural silks that can stretch and bend while retaining a high degree of strength.But while that's all well and good for spiders,bees and the like,this understanding of silk geometry could lead to new materials that are stronger and more ductile than those we can currently manufacture.Our best and strongest materials are generally expensive and difficult to produce(requiring high temperature treatments or energy-intensive processes).By looking to silk as a model,researchers could potentially devise new manufacturing methods that rely on inexpensive materials and weak bonds to create less rigid,more forgiving materials that are nonetheless stronger than anything currently on offer. And if you thought you were going to get out of this materials science story without hearing about carbon nanotubes（纳米碳管）, think again. The MIT team is already in the lab looking into ways of synthesizing silk-like structures out of materials that are stronger than natural silk-like carbon nanotubes. Super-silks are on the horizon.Silk's strength comes from its weak hydrogen bonds working together.A:RightB:WrongC:Not mentioned
考题
共用题干
New Understanding of Natural Silk's MysteriesNatural silk,as we all know,has a strength that man-made materials have long struggled to match.In a discovery that sounds more like an ancient Chinese proverb than a materials science breakthrough,MIT re- searchers have discovered that silk gets its strength from its weakness.Or,more specifically,its many weak- nesses. Silk gets its extraordinary durability and ductility（柔韧性）from an unusual arrangement of hydrogen bonds that are intrinsically very weak but that work together to create a strong,flexible structure.Most materials一especially the ones we engineer for strength一get their toughness from brittleness.As such,natural silks like those produced by spiders have long fascinated both biologists and engineers because of their light weight,ductility and high strength(pound for pound,silk is stronger than steel and far less brittle). But on its face,it doesn't seem that silks should be as strong as they are;molecularly,they are held together by hydrogen bonds , which are far weaker than the covalent（共价的）bonds found in other molecules.To get a better understanding of how silk manages to produce such strength through such weak bonds, the MIT team created a set of computer models that allowed them to observe the way silk behaves at the atomic level. They found that the arrangement of the tiny silk nanocrystals（纳米晶体）is such that the hydro- gen bonds are able to work cooperatively,reinforcing one another against external forces and failing slowlywhen they do fail,so as not to allow a sudden fracture to spread across a silk structure.The result is natural silks that can stretch and bend while retaining a high degree of strength.But while that's all well and good for spiders,bees and the like,this understanding of silk geometry could lead to new materials that are stronger and more ductile than those we can currently manufacture.Our best and strongest materials are generally expensive and difficult to produce(requiring high temperature treatments or energy-intensive processes).By looking to silk as a model,researchers could potentially devise new manufacturing methods that rely on inexpensive materials and weak bonds to create less rigid,more forgiving materials that are nonetheless stronger than anything currently on offer. And if you thought you were going to get out of this materials science story without hearing about carbon nanotubes（纳米碳管）, think again. The MIT team is already in the lab looking into ways of synthesizing silk-like structures out of materials that are stronger than natural silk-like carbon nanotubes. Super-silks are on the horizon.The MIT team had tried different materials before they studied natural silk in their research.A:RightB:WrongC:Not mentioned
考题
共用题干
第三篇The Science of the FutureUntil recently,the"science of the future"was supposed to be electronics and artificial intelligence.Today it seems more and more likely that the next great breakthroughs in technology will be brought through a combination of those two sciences with organic chemistry and genetic engineering.This combination is the science of biotechnology.Organic chemistry enables us to produce marvelous synthetic（合成的）materials. However,it is still difficult to manufacture anything that has the capacity of wool to conserve heat and also to absorb moisture.Nothing that we have been able to produce so far comes anywhere near the combination of strength,lightness and flexibility that we find in the bodies of ordinary insects.Nevertheless,scientists in the laboratory have already succeeded in"growing"a material that has many of the characteristics of human skin.The next step may well be "biotech hearts and eyes"which can replace diseased organs in human beings.These will not be rejected by the body,as is the case with organs from humans.The application of biotechnology to energy production seems even more promising.In 1 996 the famous science-fiction writer,Arthur C. Clarke,many of whose previous predictions have come true,said that we may soon be able to develop remarkably cheap and renewable sources of energy.Some of these power sources will be biological.Clarke and others have warned us repeatedly that sooner or later we will have to give up ourdependence on non-renewable power sources.Coal,oil and gas are indeed convenient. However,using them also means creating dangerously high levels of pollution.It will be impossible to meet the growing demand for energy without increasing that pollution to catastrophic（灾难性的）levels unless we develop power sources that are both cheaper and cleaner.It is attempting to think that biotechnology or some other"science of the future"can solve our problems.Before we surrender to that temptation we should remember nuclear power.Only a few generations ago it seemed to promise limitless,cheap and safe energy.Today those promises lie buried in a concrete grave in a place called Chernobyl,in the Ukraine.Biotechnology is unlikely,however,to break its promises in quite the same or such a dangerous way.Organic chemistry helps to produce materials that areA:as good as wool. B:as good as an insect's body.C:not as good as natural materials. D:better than natural materials.
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New Understanding of Natural Silk's MysteriesNatural silk,as we all know,has a strength that man-made materials have long struggled to match.In a discovery that sounds more like an ancient Chinese proverb than a materials science breakthrough,MIT re- searchers have discovered that silk gets its strength from its weakness.Or,more specifically,its many weak- nesses. Silk gets its extraordinary durability and ductility（柔韧性）from an unusual arrangement of hydrogen bonds that are intrinsically very weak but that work together to create a strong,flexible structure.Most materials一especially the ones we engineer for strength一get their toughness from brittleness.As such,natural silks like those produced by spiders have long fascinated both biologists and engineers because of their light weight,ductility and high strength(pound for pound,silk is stronger than steel and far less brittle). But on its face,it doesn't seem that silks should be as strong as they are;molecularly,they are held together by hydrogen bonds , which are far weaker than the covalent（共价的）bonds found in other molecules.To get a better understanding of how silk manages to produce such strength through such weak bonds, the MIT team created a set of computer models that allowed them to observe the way silk behaves at the atomic level. They found that the arrangement of the tiny silk nanocrystals（纳米晶体）is such that the hydro- gen bonds are able to work cooperatively,reinforcing one another against external forces and failing slowlywhen they do fail,so as not to allow a sudden fracture to spread across a silk structure.The result is natural silks that can stretch and bend while retaining a high degree of strength.But while that's all well and good for spiders,bees and the like,this understanding of silk geometry could lead to new materials that are stronger and more ductile than those we can currently manufacture.Our best and strongest materials are generally expensive and difficult to produce(requiring high temperature treatments or energy-intensive processes).By looking to silk as a model,researchers could potentially devise new manufacturing methods that rely on inexpensive materials and weak bonds to create less rigid,more forgiving materials that are nonetheless stronger than anything currently on offer. And if you thought you were going to get out of this materials science story without hearing about carbon nanotubes（纳米碳管）, think again. The MIT team is already in the lab looking into ways of synthesizing silk-like structures out of materials that are stronger than natural silk-like carbon nanotubes. Super-silks are on the horizon.MIT researchers carry out the study to illustrate an ancient Chinese proverb.A:RightB:WrongC:Not mentioned
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New Understanding of Natural Silk's MysteriesNatural silk,as we all know,has a strength that man-made materials have long struggled to match.In a discovery that sounds more like an ancient Chinese proverb than a materials science breakthrough,MIT re- searchers have discovered that silk gets its strength from its weakness.Or,more specifically,its many weak- nesses. Silk gets its extraordinary durability and ductility（柔韧性）from an unusual arrangement of hydrogen bonds that are intrinsically very weak but that work together to create a strong,flexible structure.Most materials一especially the ones we engineer for strength一get their toughness from brittleness.As such,natural silks like those produced by spiders have long fascinated both biologists and engineers because of their light weight,ductility and high strength(pound for pound,silk is stronger than steel and far less brittle). But on its face,it doesn't seem that silks should be as strong as they are;molecularly,they are held together by hydrogen bonds , which are far weaker than the covalent（共价的）bonds found in other molecules.To get a better understanding of how silk manages to produce such strength through such weak bonds, the MIT team created a set of computer models that allowed them to observe the way silk behaves at the atomic level. They found that the arrangement of the tiny silk nanocrystals（纳米晶体）is such that the hydro- gen bonds are able to work cooperatively,reinforcing one another against external forces and failing slowlywhen they do fail,so as not to allow a sudden fracture to spread across a silk structure.The result is natural silks that can stretch and bend while retaining a high degree of strength.But while that's all well and good for spiders,bees and the like,this understanding of silk geometry could lead to new materials that are stronger and more ductile than those we can currently manufacture.Our best and strongest materials are generally expensive and difficult to produce(requiring high temperature treatments or energy-intensive processes).By looking to silk as a model,researchers could potentially devise new manufacturing methods that rely on inexpensive materials and weak bonds to create less rigid,more forgiving materials that are nonetheless stronger than anything currently on offer. And if you thought you were going to get out of this materials science story without hearing about carbon nanotubes（纳米碳管）, think again. The MIT team is already in the lab looking into ways of synthesizing silk-like structures out of materials that are stronger than natural silk-like carbon nanotubes. Super-silks are on the horizon.Carbon nanotubes are currently the most popular topic in materials science.A:RightB:WrongC:Not mentioned
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Natural MedicinesSince earliest days,humans have used some kinds of medicines.We know this because humans have survived.Ancient treatments for injury and disease were successful enough to keep humans from dying out completely.They were successful long before the time of modern medicine. Before the time of doctors with white coats and shiny（发亮的）instruments. Before the time of big hospitals with strange and wonderful equipment.Many parts of the world still do not have university-educated doctors. Nor do they have expensive hospitals.Yet injuries are treated.And diseases are often cured.How?By ancient methods. By medicines that might seem mysterious , even magical（有魔力的）.Traditional medicines are neither mysterious nor magical,however.Through the centuries , tribal（部落的）medicine men experimented with plants. They found many useful chemicals in the plants.And scientists believe many of these traditional medicines may provide the cure for some of today's most serious diseases.Experts say almost 80% of the people in the world use plants for health care.These natural medicines are used not just because people have no other form of treatment. They are used because people trust them. In developed areas,few people think about the source of the medicines they buy in a store .Yet many widely-used medicines are from ancient sources,especially plants.Some experts say more than 25%of modem medicines come,in one way or another,from nature.Scientists have long known that nature is really a chemical factory. All living things contain chemicals that help them survive .So scientists' interest in traditional medicine is not new.But it has become an urgent concern.This is because the earth's supply of natural medicines may be dropping rapidly. It can be seen from the passage that the earth's supply of natural medicines______.A: may never be exhaustedB: may be dropping rapidlyC: is surprisingly bigD: is as rich as ever
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Some Things We Know About LanguageMany things about language are a mystery,and many will always remain so.But some things we do know.First , we know that all human beings have a language of some sort.There is no race（种族）of men anywhere on earth so backward that it has no language,no set of speech sounds by which the people communicate with one another.Furthermore,in historical times,there has never been a race of men without a language. Second,there is no such thing as a primitive（原始的）language.There are many people whose cultures are undeveloped,who are,as we say,uncivilized,but the languages they speak are not primitive.In all known languages we can see complexities that must have been tens of thousands of years in developing. This has not always been well understood;indeed,the direct contrary has often been stated.Popular ideas of the language of the American Indians will illustrate.Many people have supposed that the Indians communicated in a very primitive system of noises.Study has proved this to be nonsense.There are,or were, hundreds of American Indian languages,and all of them turn out to be very complicated and very old.They are certainly different from the languages that most of us are familiar with,but they are no more primitive than English and Greek.A third thing we know about language is that all languages are perfectly adequate.That is,each one is a perfect means of expressing the culture of the people who speak the language. Finally,we know that language changes.It is natural and normal for language to change;the only languages which do not change are the dead ones.This is easy to understand if we look backward in time. Change goes on in all aspects of language.Grammatical features change as do speech sounds,and changes in vocabulary are sometimes very extensive and may occur very rapidly.Vocabulary is the least stable part of any language.According to the third paragraph,the author thinks that______.A:there exist some primitive languages in the worldB:there are many people who don't have a languageC:no languages in the world haven't been well developedD:there are some languages we know having little complexities
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Some Things We Know About LanguageMany things about language are a mystery,and many will always remain so.But some things we do know.First , we know that all human beings have a language of some sort.There is no race（种族）of men anywhere on earth so backward that it has no language,no set of speech sounds by which the people communicate with one another.Furthermore,in historical times,there has never been a race of men without a language. Second,there is no such thing as a primitive（原始的）language.There are many people whose cultures are undeveloped,who are,as we say,uncivilized,but the languages they speak are not primitive.In all known languages we can see complexities that must have been tens of thousands of years in developing. This has not always been well understood;indeed,the direct contrary has often been stated.Popular ideas of the language of the American Indians will illustrate.Many people have supposed that the Indians communicated in a very primitive system of noises.Study has proved this to be nonsense.There are,or were, hundreds of American Indian languages,and all of them turn out to be very complicated and very old.They are certainly different from the languages that most of us are familiar with,but they are no more primitive than English and Greek.A third thing we know about language is that all languages are perfectly adequate.That is,each one is a perfect means of expressing the culture of the people who speak the language. Finally,we know that language changes.It is natural and normal for language to change;the only languages which do not change are the dead ones.This is easy to understand if we look backward in time. Change goes on in all aspects of language.Grammatical features change as do speech sounds,and changes in vocabulary are sometimes very extensive and may occur very rapidly.Vocabulary is the least stable part of any language.The author argues that we do know some things about language in______aspects.A:three B:fourC:five D:six
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Some Things We Know About LanguageMany things about language are a mystery,and many will always remain so.But some things we do know.First , we know that all human beings have a language of some sort.There is no race（种族）of men anywhere on earth so backward that it has no language,no set of speech sounds by which the people communicate with one another.Furthermore,in historical times,there has never been a race of men without a language. Second,there is no such thing as a primitive（原始的）language.There are many people whose cultures are undeveloped,who are,as we say,uncivilized,but the languages they speak are not primitive.In all known languages we can see complexities that must have been tens of thousands of years in developing. This has not always been well understood;indeed,the direct contrary has often been stated.Popular ideas of the language of the American Indians will illustrate.Many people have supposed that the Indians communicated in a very primitive system of noises.Study has proved this to be nonsense.There are,or were, hundreds of American Indian languages,and all of them turn out to be very complicated and very old.They are certainly different from the languages that most of us are familiar with,but they are no more primitive than English and Greek.A third thing we know about language is that all languages are perfectly adequate.That is,each one is a perfect means of expressing the culture of the people who speak the language. Finally,we know that language changes.It is natural and normal for language to change;the only languages which do not change are the dead ones.This is easy to understand if we look backward in time. Change goes on in all aspects of language.Grammatical features change as do speech sounds,and changes in vocabulary are sometimes very extensive and may occur very rapidly.Vocabulary is the least stable part of any language.According to the author,language changes are most likely to occur in______.A:grammar B:pronunciationC:vocabulary D:intonation
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Some Things We Know About LanguageMany things about language are a mystery,and many will always remain so.But some things we do know.First , we know that all human beings have a language of some sort.There is no race（种族）of men anywhere on earth so backward that it has no language,no set of speech sounds by which the people communicate with one another.Furthermore,in historical times,there has never been a race of men without a language. Second,there is no such thing as a primitive（原始的）language.There are many people whose cultures are undeveloped,who are,as we say,uncivilized,but the languages they speak are not primitive.In all known languages we can see complexities that must have been tens of thousands of years in developing. This has not always been well understood;indeed,the direct contrary has often been stated.Popular ideas of the language of the American Indians will illustrate.Many people have supposed that the Indians communicated in a very primitive system of noises.Study has proved this to be nonsense.There are,or were, hundreds of American Indian languages,and all of them turn out to be very complicated and very old.They are certainly different from the languages that most of us are familiar with,but they are no more primitive than English and Greek.A third thing we know about language is that all languages are perfectly adequate.That is,each one is a perfect means of expressing the culture of the people who speak the language. Finally,we know that language changes.It is natural and normal for language to change;the only languages which do not change are the dead ones.This is easy to understand if we look backward in time. Change goes on in all aspects of language.Grammatical features change as do speech sounds,and changes in vocabulary are sometimes very extensive and may occur very rapidly.Vocabulary is the least stable part of any language.The author has used American Indian language to illustrate______.A:it hasn't been well understood that there is no primitive languageB:the Indians communicated in a very primitive system of noisesC:English and Greek are less primitive than American Indian languagesD:hundreds of American Indian languages are easy and young
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Some Things We Know About LanguageMany things about language are a mystery,and many will always remain so.But some things we do know.First , we know that all human beings have a language of some sort.There is no race（种族）of men anywhere on earth so backward that it has no language,no set of speech sounds by which the people communicate with one another.Furthermore,in historical times,there has never been a race of men without a language. Second,there is no such thing as a primitive（原始的）language.There are many people whose cultures are undeveloped,who are,as we say,uncivilized,but the languages they speak are not primitive.In all known languages we can see complexities that must have been tens of thousands of years in developing. This has not always been well understood;indeed,the direct contrary has often been stated.Popular ideas of the language of the American Indians will illustrate.Many people have supposed that the Indians communicated in a very primitive system of noises.Study has proved this to be nonsense.There are,or were, hundreds of American Indian languages,and all of them turn out to be very complicated and very old.They are certainly different from the languages that most of us are familiar with,but they are no more primitive than English and Greek.A third thing we know about language is that all languages are perfectly adequate.That is,each one is a perfect means of expressing the culture of the people who speak the language. Finally,we know that language changes.It is natural and normal for language to change;the only languages which do not change are the dead ones.This is easy to understand if we look backward in time. Change goes on in all aspects of language.Grammatical features change as do speech sounds,and changes in vocabulary are sometimes very extensive and may occur very rapidly.Vocabulary is the least stable part of any language.Which of the following statements is INCORRECT?A:A language is a means of expressing a particular culture.B:All languages can well express their respective cultures.C:American Indian languages are as complex as English.D:Some languages are better than others.
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Some Things We Know About LanguageMany things about language are a mystery,and many will always remain so.But some things we do know.First,we know that all human beings have a language of some sort. There is no race of men anywhere on earth so backward that it has no language,no set of speech sounds by which the people communicate with one another. Furthermore,in historical times,there has never been a race of men without a language.Second,there is no such thing as a primitive language.There are many people whose cultures are undeveloped,who are,as we say,uncivilized,but the languages they speak are not primitive .In all known languages we can see complexities that must have been tens of thousands of years in developing.This has not always been well understood;indeed,the direct contrary has often been stated.Popular ideas of the language of the American Indians will illustrate.Many people have supposed that the Indians communicated in a very primitive system of noises.Study has proved this to be nonsense .There are,or were,hundreds of American Indian languages,and all of them turn out to be very complicated and very old.They are certainly different from the languages that most of us are familiar with,but they are no more primitive than English and Greek.A third thing we know about language is that all languages are perfectly adequate. That is, each one is a perfect means of expressing the culture of the people who speak the language.Finally,we know that language changes.It is natural and normal for language to change;the only languages which do not change are the dead ones.This is easy to understand if we look backward in time.Change goes on in all aspects of language.Grammatical teatures change as do speech sounds,and changes in vocabulary are sometimes very extensive and may occur very rap-idly. Vocabulary is the least stable part of any language. According to the author,language changes are most likely to occur in______.A: grammarB: pronunciationC: vocabularyD: intonation
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Some Things We Know About LanguageMany things about language are a mystery,and many will always remain so.But some things we do know.First,we know that all human beings have a language of some sort. There is no race of men anywhere on earth so backward that it has no language,no set of speech sounds by which the people communicate with one another. Furthermore,in historical times,there has never been a race of men without a language.Second,there is no such thing as a primitive language.There are many people whose cultures are undeveloped,who are,as we say,uncivilized,but the languages they speak are not primitive .In all known languages we can see complexities that must have been tens of thousands of years in developing.This has not always been well understood;indeed,the direct contrary has often been stated.Popular ideas of the language of the American Indians will illustrate.Many people have supposed that the Indians communicated in a very primitive system of noises.Study has proved this to be nonsense .There are,or were,hundreds of American Indian languages,and all of them turn out to be very complicated and very old.They are certainly different from the languages that most of us are familiar with,but they are no more primitive than English and Greek.A third thing we know about language is that all languages are perfectly adequate. That is, each one is a perfect means of expressing the culture of the people who speak the language.Finally,we know that language changes.It is natural and normal for language to change;the only languages which do not change are the dead ones.This is easy to understand if we look backward in time.Change goes on in all aspects of language.Grammatical teatures change as do speech sounds,and changes in vocabulary are sometimes very extensive and may occur very rap-idly. Vocabulary is the least stable part of any language. The author has used American Indian languages as an example to show that they are______.A: just as old as some well-known languagesB: just as sophisticated as some well-known languagesC: more developed than some well-known languagesD: more complex than some well-known languages
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Some Things We Know About LanguageMany things about language are a mystery,and many will always remain so.But some things we do know.First,we know that all human beings have a language of some sort. There is no race of men anywhere on earth so backward that it has no language,no set of speech sounds by which the people communicate with one another. Furthermore,in historical times,there has never been a race of men without a language.Second,there is no such thing as a primitive language.There are many people whose cultures are undeveloped,who are,as we say,uncivilized,but the languages they speak are not primitive .In all known languages we can see complexities that must have been tens of thousands of years in developing.This has not always been well understood;indeed,the direct contrary has often been stated.Popular ideas of the language of the American Indians will illustrate.Many people have supposed that the Indians communicated in a very primitive system of noises.Study has proved this to be nonsense .There are,or were,hundreds of American Indian languages,and all of them turn out to be very complicated and very old.They are certainly different from the languages that most of us are familiar with,but they are no more primitive than English and Greek.A third thing we know about language is that all languages are perfectly adequate. That is, each one is a perfect means of expressing the culture of the people who speak the language.Finally,we know that language changes.It is natural and normal for language to change;the only languages which do not change are the dead ones.This is easy to understand if we look backward in time.Change goes on in all aspects of language.Grammatical teatures change as do speech sounds,and changes in vocabulary are sometimes very extensive and may occur very rap-idly. Vocabulary is the least stable part of any language. In the second paragraph the passage tells us that______.A: some backward race doesn't have a language of its ownB: some race in history didn't possess a language of its ownC: any human race,whether backward or not,has a languageD: some races on earth can communicate without language
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Some Things We Know About LanguageMany things about language are a mystery,and many will always remain so.But some things we do know.First,we know that all human beings have a language of some sort. There is no race of men anywhere on earth so backward that it has no language,no set of speech sounds by which the people communicate with one another. Furthermore,in historical times,there has never been a race of men without a language.Second,there is no such thing as a primitive language.There are many people whose cultures are undeveloped,who are,as we say,uncivilized,but the languages they speak are not primitive .In all known languages we can see complexities that must have been tens of thousands of years in developing.This has not always been well understood;indeed,the direct contrary has often been stated.Popular ideas of the language of the American Indians will illustrate.Many people have supposed that the Indians communicated in a very primitive system of noises.Study has proved this to be nonsense .There are,or were,hundreds of American Indian languages,and all of them turn out to be very complicated and very old.They are certainly different from the languages that most of us are familiar with,but they are no more primitive than English and Greek.A third thing we know about language is that all languages are perfectly adequate. That is, each one is a perfect means of expressing the culture of the people who speak the language.Finally,we know that language changes.It is natural and normal for language to change;the only languages which do not change are the dead ones.This is easy to understand if we look backward in time.Change goes on in all aspects of language.Grammatical teatures change as do speech sounds,and changes in vocabulary are sometimes very extensive and may occur very rap-idly. Vocabulary is the least stable part of any language. According to the author,people of undeveloped cultures can have______languages.A: complicatedB: uncivilizedC: primitiveD: well-known
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问答题Practice 1 We have learned from our Embassy that you are interested in importing Chinese silk products. We are a long-established exporter of silk products in China and we have a very good reputation both at home and abroad. Our products sell well all over the world and highly valued by our customers for their excellent quality and fine workmanship(工艺). Enclosed are our catalogue and price list covering all the products. We are looking forward to your early reply.
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问答题Green Gene Technology For the past 10,000 years humans have influenced the plants they use at first unknowingly, later by design. Today’s crops have been created by a process of selection and classical breeding. More specific improvements in breeding will be possible in future. Science has cracked the genetic information code. Green gene technology is an effective tool in crop breeding, enabling us to develop new crops even more rapidly and specifically. We can make them more efficient, optimizing their contents and valuable substances to suit the wishes and requirements of customers and the processing industry. Their metabolism can be individually modified, making them produce starch, protein and fats with special properties. Through gene transfer plants can be made more resistant to viruses, bacteria, harmful fungi and insect pests. Genetically modified plants can be cultivated to possess improved stress behavior, with the result that they absorb water better in dry locations and can make more efficient use of soil nutrients. We can also optimize weed control. To do so, we make crops tolerant to environmentally sound and easily degradable herbicides. This is not as simple as it sounds. But we have been successful: Innovator has been on the Canadian market since 1995. This is the first oilseed rape variety to contain the glufosinate tolerance gene, facilitating the use of AgrEvo’s broad-spectrum herbicide liberty. We are committed to green gene technology, with which we aim to make crop breeding even more efficient and environmentally friendly. Before being brought on to the market these genetically modified plants are researched and tested for years until the questions posed regarding their safety have been answered. This is a great opportunity for us to realize our vision: the use of faster methods to breed varieties which will continue to provide us with sufficient food and raw materials in future. Our fossil reserves will soon be exhausted. Experts estimate that we only have enough oil for another 43 years and natural gas for less than 60. This means we must rethink and act accordingly, using new crop varieties to step up the move to replenishable sources of raw materials and energy. In other words, green gene technology is the key technology for sustainable agriculture.
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