单选题Which of the following is NOT mentioned as the result of artificial selection by humanity?A Many new kinds of plants and animals are produced.B Financial gain is increased considerably by producing better plants and animals.C Humans are able to control plant and animal reproduction for humans’ pleasure.D It is necessary for humans to maintain the artificial environments.

考题 Which of the following is the result of the volcanic eruption?A. People stop traveling in EuropeB. Airlines suffer from the loss of planesC. It becomes dangerous for animals to eat outsideD. Farmers have lost many of their animals

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考题 Passage TwoQuestions 26 to 30 are based on the following passage.Certain animals and plants develop characteristics(特性)that help them cope with their environment better than others of their kind. This natural biological process is called adaptation(适应性). Among the superior characteristics developed through adaptation are those that may help in getting food or shelter，in providing protection，and in producing and protecting the young. That results in the evolution of more and more organisms that are better fitted to their environments.Each living thing is adapted to its way of life in a general way，but each is adapted especially to its own distinct class. A plant，for example，depends upon its roots to fix itself firmly and to absorb water and inorganic chemicals. It depends upon its green leaves for using the sun's energy to make food from inorganic chemicals. These are general adaptations，common to most plants. In addition，there are special adaptations that only certain kinds of plants have. Many animals have adaptations that help them escape from their enemies. Some insects are hidden by their body color or shape，and many look like a leaf or a little branch. The coats of deer are colored to mix with the surroundings. Many animals have the ability to remain completely still when an enemy is near.Organisms have a great variety of ways for adapting. They may adapt in their structure，function，and genetics(遗传素质)；in their development and production of the young；and in other respects. An organism may create its own environment，as do warm-blooded mammals. which have the ability to adjust body heat exactly to maintain their ideal temperature despite changing weather. Usually adaptations are an advantage，but sometimes an organism is so well adapted to a particular environment that，if conditions Change，it finds it difficult or impossible to readapt to the new conditions.Some plants and animals develop superior characteristics so that they may______.A. help others of their kind get food，shelter and other things neededB. get into the biological process of adaptationC. become better adapted to the environments than others of their kindD. lead to the evolution and production of more and more organisms

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考题 Most animals have little connection with animals of different kind, unless they hunt them for food. Sometimes, however, two kinds of animals come together in a partnership ( 伙伴关系 ) which does good to both of them. You may have noticed some birds sitting on the backs of sheep. This is not because they want a ride, but because they find easy food in the parasites (寄生虫 ) on sheep. The sheep allow the birds to do so because they remove the cause of discomfort. So although they can manage without each other, they do better together.Sometimes an animal has a plant partner. The relationship develops until the two partners cannot manage without each other. This is so in the corals ( 珊瑚 ) of the sea. In their skins they have tiny plants act as "dustman", taking some of the waste products form. the corals and giving in return oxygen which the animal needs to breathe. If the plants are killed, or are ever prevented from lighting so that they cannot live normally, the corals will die.1、Some birds like to sit on a sheep because ( ).A、they can eat its parasitesB、 they depend on the sheep for existenceC、 they enjoy traveling with the sheepD、 they find the position most comfortable2、The underlined word "they" in the last sentence of the first paragraph refers to ( ).A、birds and parasitesB、birds and sheepC、parasites and sheepD、sheep, birds and parasites3、What does the second paragraph mainly discuss? ( )A、Some animals and plants depend on each other for existence.B、 Some animals and plants develop their relationship easily.C、 Some plants depend on each other for fooD、 Some animals live better together.4、What does this article talk about? ( )A、Two kinds of animals for a partnership.B、Most animals only have connection with animals.C、The connection between the living things.D、Corals have some connection with plants.

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考题 All animals including men feed on plants or other animals. (英译汉)

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考题 It was long supposed ____ the main difference between animals and plants was that animals could move about.A: whichB: thisC: thatD: because

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考题 Animals can move about ____ plants cannot.A: whileB: whenC: becauseD: for

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考题 Many animals ____ green plants for their food.A. carry outB. base onC. depend onD. look for

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考题 most of australia’s unique plants and animals are imported from other continents. ()

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考题 29． Which of the following is NOT true?A． In 1884，George Eastman invented a kind of film．B． Deep-sea divers take pictures of ocean plants and animals．C， The films were developed by the owners of the cameras in the pastD． Astronauts use cameras to take f，photos in space

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考题共用题干 Adaptation of Living ThingsCertain animals and plants develop characteristics that help them cope with their environment better than others of their kind.This natural biological process is called adaptation.Among the superior characteristics developed through adaptationare those that may help in getting food or shelter,in providing protection,and in producing and protecting the young.That results in the evolution of more and more organisms（微生物）that are better fitted to their environments.Each living thing is adapted to its way of life in a general way,but each is adapted especially to its own distinct class.A plant,for example,depends upon its roots to fix itself firmly and to absorb water and inorganic（无机的）chemicals.It depends upon its green leaves for using the sun's energy to make food from inorganic chemicals.These are general adaptations,common to most plants.In addition,there are special adaptations that only certain kinds of plants have.Many animals have adaptations that help them escape from their enemies.Some insects are hidden by their body color or shape,and many look like a leaf or a little branch.The coats of deer are colored to mix with the surroundings.Many animals have the ability to remain completely still when an enemy is near.Organisms have a great variety of ways of adapting.They may adapt.in their structure,function,and genetics;in their development and production of the young;and in other respects.An organism may create its own environment,as do warm-blooded mammals（哺乳动物）,which have the ability to adjust body heat exactly to maintain their ideal temperature despite changing weather.Usually adaptations are an advantage,but sometimes an organism is so well adapted to a particular environment that,if conditions change,it finds it difficult or impossible to readapt to the new conditions.The author cites the behavior of warm-blooded mammals in order to illustrate that______.A:a living thing may have the ability to create an environment of its ownB:a living creature may have the ability to remain still when an enemy is nearC:a living creature may have the ability to make food from its inorganic chemicalsD:a living creature may have the ability to change the color of its skin

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考题共用题干 Adaptation of Living ThingsCertain animals and plants develop characteristics that help them cope with their environment better than others of their kind.This natural biological process is called adaptation.Among the superior characteristics developed through adaptation are those that may help in getting food or shelter,in providing protection,and in producing and protecting the young. That results in the evolution of more and more organisms（生物体）that are better fitted to their environments.Each living thing is adapted to its way of life in a general way,but each is adapted especially to its own distinct class.A plant,for example,depends upon its roots to fix itself firmly and toabsorb water and inorganic chemicals（无机物）.It depends upon its green leaves for using the sun's energy to make food from inorganic chemicals.These are general adaptations,common to most plants .In addition,there are special adaptations that only certain kinds of plants have.Many animals have adaptations that help them escape from their enemies.Some are hidden by their body color or shape,and many look like a leaf or a little branch.The coats of deer are colored to mix with the surroundings .Many animals .have the ability to remain completely still when an enemy is near.Organisms have a great variety of ways of adapting.They may adapt in their structure,func-tion,and genetics;in their development and production of the young;and in other respects.An organism may create its own environment, as do warm-blooded mammals（哺乳动物）,which have the ability to adjust body heat exactly to maintain their ideal temperature despite changing weather.Usually adaptations are an advantage,but sometimes an organism is so well adapted to a particular environment that if conditions change,it finds it difficult or impossible to readapt to the new conditions. Which of the following is NOT directly mentioned in the passage?A: A living thing may adapt in its structure.B: An organism may adapt in its function.C: A living creature may adapt in its genetic makeup.D: A living organism may adapt in its sleeping habit.

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考题共用题干 Adaptation of Living ThingsCertain animals and plants develop characteristics that help them cope with their environment better than others of their kind.This natural biological process is called adaptation.Among the superior characteristics developed through adaptation are those that may help in getting food or shelter,in providing protection,and in producing and protecting the young. That results in the evolution of more and more organisms（生物体）that are better fitted to their environments.Each living thing is adapted to its way of life in a general way,but each is adapted especially to its own distinct class.A plant,for example,depends upon its roots to fix itself firmly and toabsorb water and inorganic chemicals（无机物）.It depends upon its green leaves for using the sun's energy to make food from inorganic chemicals.These are general adaptations,common to most plants .In addition,there are special adaptations that only certain kinds of plants have.Many animals have adaptations that help them escape from their enemies.Some are hidden by their body color or shape,and many look like a leaf or a little branch.The coats of deer are colored to mix with the surroundings .Many animals .have the ability to remain completely still when an enemy is near.Organisms have a great variety of ways of adapting.They may adapt in their structure,func-tion,and genetics;in their development and production of the young;and in other respects.An organism may create its own environment, as do warm-blooded mammals（哺乳动物）,which have the ability to adjust body heat exactly to maintain their ideal temperature despite changing weather.Usually adaptations are an advantage,but sometimes an organism is so well adapted to a particular environment that if conditions change,it finds it difficult or impossible to readapt to the new conditions. It can be inferred from this passage that the feathers of a bird are colored_______.A: to frightened its enemiesB: to attract its enemiesC:to adjust its body heatD:to match its environment

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考题共用题干 Adaptation of Living ThingsCertain animals and plants develop characteristics that help them cope with their environment better than others of their kind.This natural biological process is called adaptation.Among the superior characteristics developed through adaptation are those that may help in getting food or shelter,in providing protection,and in producing and protecting the young. That results in the evolution of more and more organisms（生物体）that are better fitted to their environments.Each living thing is adapted to its way of life in a general way,but each is adapted especially to its own distinct class.A plant,for example,depends upon its roots to fix itself firmly and toabsorb water and inorganic chemicals（无机物）.It depends upon its green leaves for using the sun's energy to make food from inorganic chemicals.These are general adaptations,common to most plants .In addition,there are special adaptations that only certain kinds of plants have.Many animals have adaptations that help them escape from their enemies.Some are hidden by their body color or shape,and many look like a leaf or a little branch.The coats of deer are colored to mix with the surroundings .Many animals .have the ability to remain completely still when an enemy is near.Organisms have a great variety of ways of adapting.They may adapt in their structure,func-tion,and genetics;in their development and production of the young;and in other respects.An organism may create its own environment, as do warm-blooded mammals（哺乳动物）,which have the ability to adjust body heat exactly to maintain their ideal temperature despite changing weather.Usually adaptations are an advantage,but sometimes an organism is so well adapted to a particular environment that if conditions change,it finds it difficult or impossible to readapt to the new conditions. The author cites the behavior of warm-blooded mammals in order to illustrate that a living thing may have the ability_______.A:to create an environment of its ownB:to remain still when an enemy is near.C:to make food from its inorganic chemicalsD:to change the color of its skin.

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考题共用题干 Adaptation of Living ThingsCertain animals and plants develop characteristics that help them cope with their environment better than others of their kind.This natural biological process is called adaptation.Among the superior characteristics developed through adaptation are those that may help in getting food or shelter,in providing protection,and in producing and protecting the young. That results in the evolution of more and more organisms（生物体）that are better fitted to their environments.Each living thing is adapted to its way of life in a general way,but each is adapted especially to its own distinct class.A plant,for example,depends upon its roots to fix itself firmly and toabsorb water and inorganic chemicals（无机物）.It depends upon its green leaves for using the sun's energy to make food from inorganic chemicals.These are general adaptations,common to most plants .In addition,there are special adaptations that only certain kinds of plants have.Many animals have adaptations that help them escape from their enemies.Some are hidden by their body color or shape,and many look like a leaf or a little branch.The coats of deer are colored to mix with the surroundings .Many animals .have the ability to remain completely still when an enemy is near.Organisms have a great variety of ways of adapting.They may adapt in their structure,func-tion,and genetics;in their development and production of the young;and in other respects.An organism may create its own environment, as do warm-blooded mammals（哺乳动物）,which have the ability to adjust body heat exactly to maintain their ideal temperature despite changing weather.Usually adaptations are an advantage,but sometimes an organism is so well adapted to a particular environment that if conditions change,it finds it difficult or impossible to readapt to the new conditions. Some plants and animals develop superior characteristics so that they may＿____.A: help others of their kind get food,shelter and other things neededB: survive even in extremely severe conditionsC: become better adapted to the environments than others of their kindD: result in the evolution and production of more intelligent organisms

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考题共用题干 Ecosystem1. The word “ecosystem” is short for ecological（生态的）system. An ecosystem is where living creatures expand within a given area. You can say that an ecosystem is the natural environment where biological organisms（生物）such as plants,animals and humans co-exist in this world. So naturally that includes you and me. Yes,we are all members of an ecosystem!2 .There are different kinds of ecosystems depending on the type of surface or environ-ment. Most are naturally made such as the ocean or lake and the desert or rainforest.Some are man-made or artificial to encourage co-habitation（同居）between living and non-living things in a monitored environment,such as a zoo or garden.3 .Plants make up the biggest group of biological creatures within an ecosystem,and that's because they are the natural food producers for everyone. Plants raised in the earth need air and collect sunlight to help them grow. When they grow,the plants and its fruits or flowers eventually become a source of food to animals,microorganisms（微生物）and even hu- mans,of course. Food is then converted to energy for the rest of us to function,and this hap-pens in a never-ending cycle until the living creatures die and break up back in the earth.4 .Ecosystems are the basis of survival for all living things.We depend on plants and ani-mals for food. In order for us to exist,we need to grow and care about other organisms. We also need to care for the non-living things within our environment like our air and water so we can continue living as a population. Since plants,animals and humans are all of various species（物种）,we all play a role in maintaining the ecosystem.5 .To preserve our ecosystems,we should stop using too much energy,which happens when we consume more than our share of resources. Humans should not disturb the natural habitat（栖息地）of plants and animals,and allow them to grow healthily for the cycle to con-tinue. Too many people in a habitat can mean displacement（搬迁）: imagine being thrown out of your home because there is no more space for everyone. Worse,overpopulation can also ru- in the environment and cause destruction of existing plants and animals.Plants,animals and humans are all effective in______.A: our share of resourcesB: a biological creatureC: a given areaD: the maintenance of the ecosystemE: the source of foodF: various species

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考题共用题干 Ecosystem1. The word “ecosystem” is short for ecological（生态的）system. An ecosystem is where living creatures expand within a given area. You can say that an ecosystem is the natural environment where biological organisms（生物）such as plants,animals and humans co-exist in this world. So naturally that includes you and me. Yes,we are all members of an ecosystem!2 .There are different kinds of ecosystems depending on the type of surface or environ-ment. Most are naturally made such as the ocean or lake and the desert or rainforest.Some are man-made or artificial to encourage co-habitation（同居）between living and non-living things in a monitored environment,such as a zoo or garden.3 .Plants make up the biggest group of biological creatures within an ecosystem,and that's because they are the natural food producers for everyone. Plants raised in the earth need air and collect sunlight to help them grow. When they grow,the plants and its fruits or flowers eventually become a source of food to animals,microorganisms（微生物）and even hu- mans,of course. Food is then converted to energy for the rest of us to function,and this hap-pens in a never-ending cycle until the living creatures die and break up back in the earth.4 .Ecosystems are the basis of survival for all living things.We depend on plants and ani-mals for food. In order for us to exist,we need to grow and care about other organisms. We also need to care for the non-living things within our environment like our air and water so we can continue living as a population. Since plants,animals and humans are all of various species（物种）,we all play a role in maintaining the ecosystem.5 .To preserve our ecosystems,we should stop using too much energy,which happens when we consume more than our share of resources. Humans should not disturb the natural habitat（栖息地）of plants and animals,and allow them to grow healthily for the cycle to con-tinue. Too many people in a habitat can mean displacement（搬迁）: imagine being thrown out of your home because there is no more space for everyone. Worse,overpopulation can also ru- in the environment and cause destruction of existing plants and animals.To protect our ecosystems we should not use more than______.A: our share of resourcesB: a biological creatureC: a given areaD: the maintenance of the ecosystemE: the source of foodF: various species

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考题共用题干 Ecosystem1. The word “ecosystem” is short for ecological（生态的）system. An ecosystem is where living creatures expand within a given area. You can say that an ecosystem is the natural environment where biological organisms（生物）such as plants,animals and humans co-exist in this world. So naturally that includes you and me. Yes,we are all members of an ecosystem!2 .There are different kinds of ecosystems depending on the type of surface or environ-ment. Most are naturally made such as the ocean or lake and the desert or rainforest.Some are man-made or artificial to encourage co-habitation（同居）between living and non-living things in a monitored environment,such as a zoo or garden.3 .Plants make up the biggest group of biological creatures within an ecosystem,and that's because they are the natural food producers for everyone. Plants raised in the earth need air and collect sunlight to help them grow. When they grow,the plants and its fruits or flowers eventually become a source of food to animals,microorganisms（微生物）and even hu- mans,of course. Food is then converted to energy for the rest of us to function,and this hap-pens in a never-ending cycle until the living creatures die and break up back in the earth.4 .Ecosystems are the basis of survival for all living things.We depend on plants and ani-mals for food. In order for us to exist,we need to grow and care about other organisms. We also need to care for the non-living things within our environment like our air and water so we can continue living as a population. Since plants,animals and humans are all of various species（物种）,we all play a role in maintaining the ecosystem.5 .To preserve our ecosystems,we should stop using too much energy,which happens when we consume more than our share of resources. Humans should not disturb the natural habitat（栖息地）of plants and animals,and allow them to grow healthily for the cycle to con-tinue. Too many people in a habitat can mean displacement（搬迁）: imagine being thrown out of your home because there is no more space for everyone. Worse,overpopulation can also ru- in the environment and cause destruction of existing plants and animals.Plants are essential in an ecosystem because to other living creatures they are______.A: our share of resourcesB: a biological creatureC: a given areaD: the maintenance of the ecosystemE: the source of foodF: various species

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考题共用题干 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. Which of the following statements is NOT true?A: Modern medicines are now available all over the world.B: Many big and modern hospitals are expensive.C: Traditional medicines are neither mysterious nor magical.D: Humans have used some kinds of medicines since earliest days.

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考题共用题干 Ecosystem1 The word " ecosystem" is short for ecological（生态的）system. An ecosystem is where living crea- tures expand within a given area.You can say that an ecosystem is the natural environment where biologicalorganisms（生物）such as plants,animals and humans co-exist in this world. So naturally that includes you and mne.Yes,we are all members of an ecosystem!2 There are different kinds of ecosystems depending on the type of suiface or environment. Most are naturally made 5uch as the ocean or lake and the desert or rainforest.Some are man-made or artificial to en- courage co-habitation（共居）between living and non-living things in a monitored environment,such as azoo or garden.3 Plants make up the biggest group of biological creatures within an ecosystem,and that's because they are the natural food producers for everyone.Plants raised in the earth need air and collect sunlight to help them grow.When they grow,the plants and their加its or flowers eventually become a source of food to animals,microorganisms (微生物）and even humans, of course. Food is then converted to energy for the rest of us to function,and this happens in a never-ending cycle until the living creatures die and break up back in the earth.4 Ecosystems are the basis of survival for all living things.We depend on plants and animals for food. In order for us to exist,we need to grow and care about other organisms.We also need tO care for the non一living things within our environment like our air and water so we can continue living as a population.Since plants, animals and humans are all of various species（物种）,we all play a role in maintaining the ecosystem.5 To preserve our ecosystems,we should stop using too much energy,which happens汕en we consume more than our share of resources. Humans should not disturb the natural habitat（栖息地）of plants and animals, and should allow them to grow healthily for the cycle to continue.Too many people in a habitat can mean dis- placement（搬迁）:imagine being thrown out of your home because there is no more space for everyone. Worse,overpopulation can also ruin the environment and cause destruction of existing plants and animals. Paragraph 3_______A: What Can We Do to Help Protect Ecosystems?B:What Are Different Types of Ecosystems？ C:What Is an Ecosystem？D: What Destroys Ecosystems? E:How does an Ecosystem Work?F: Why Are Ecosystems Important？

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考题共用题干 Ecosystem1 The word " ecosystem" is short for ecological（生态的）system. An ecosystem is where living crea- tures expand within a given area.You can say that an ecosystem is the natural environment where biologicalorganisms（生物）such as plants,animals and humans co-exist in this world. So naturally that includes you and mne.Yes,we are all members of an ecosystem!2 There are different kinds of ecosystems depending on the type of suiface or environment. Most are naturally made 5uch as the ocean or lake and the desert or rainforest.Some are man-made or artificial to en- courage co-habitation（共居）between living and non-living things in a monitored environment,such as azoo or garden.3 Plants make up the biggest group of biological creatures within an ecosystem,and that's because they are the natural food producers for everyone.Plants raised in the earth need air and collect sunlight to help them grow.When they grow,the plants and their加its or flowers eventually become a source of food to animals,microorganisms (微生物）and even humans, of course. Food is then converted to energy for the rest of us to function,and this happens in a never-ending cycle until the living creatures die and break up back in the earth.4 Ecosystems are the basis of survival for all living things.We depend on plants and animals for food. In order for us to exist,we need to grow and care about other organisms.We also need tO care for the non一living things within our environment like our air and water so we can continue living as a population.Since plants, animals and humans are all of various species（物种）,we all play a role in maintaining the ecosystem.5 To preserve our ecosystems,we should stop using too much energy,which happens汕en we consume more than our share of resources. Humans should not disturb the natural habitat（栖息地）of plants and animals, and should allow them to grow healthily for the cycle to continue.Too many people in a habitat can mean dis- placement（搬迁）:imagine being thrown out of your home because there is no more space for everyone. Worse,overpopulation can also ruin the environment and cause destruction of existing plants and animals.In an ecosystem,plants,animals and humans live together in________.A:our share of resoureesB:a biological creatureC:a given areaD:the maintenance of the ecosystemE:the source of foodF:various species

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考题单选题As they pertain to the near road mentioned in line 29, the life cycles mentioned in line 28 are those of ______.A the plants that are destroyed by road constructionB the animals that may be displaced by a new roadC economic and industrial trendsD the substances that constitute the roadE the companies involved in constructing the road

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考题单选题Why do some people get sick after drinking the water from the river?A Because the river is pollutedB Because the river makes the earth more beautifulC Because the river can only offer water to animalsD Because there are too many animals and plants in the river

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考题单选题Some people argue that it would do more harm than good for plants and animals to develop through artificial selection. Which statement best supports this argument?A Roses no longer smell like roses.B Purebred dogs are disappearing.C Humans are harmful agents of plant and animal evolution.D Many domesticated plants and animals can no longer survive in the wild.

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考题单选题Which of the following is NOT among the solutions to the lack of sewage water treatment plants?A Cooperation with other organizations.B Cooperation with the World Bank.C Two projects about treatment plants for sewage waters in Vlore and Pogradec.D To control the waste water discharged.

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考题单选题As a defense against air-pollution damage, many plants and animals _____ a substance to absorb harmful chemicals.A relieveB releaseC dismissD discard

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考题单选题Which of the following fails to tell what birds do according to the passage?A They help plants grow in miraculous ways.B They clean up the dead bodies of fish and animals.C They keep the oceans from being polluted and acidic.D They are likely to attack those irresponsible hunters.

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考题问答题Practice 2　　Transgenic plants and animals result from genetic engineering experiments in which genetic material is moved from one organism to another, so that the latter will exhibit a characteristic. Business corporations, scientists, and farmers hope that transgenic techniques will allow more cost-effective and precise plants and animals with desirable characteristics that are not available using up to date breeding technology.　　Transgenic techniques allow genetic material to be transferred between completely unrelated organisms.　　In order for a transgenic technique to work, the genetic engineer must first construct a transgene, which is the gene to be introduced plus a control sequence. When making a transgene, scientists usually substitute the original promoter sequence with one that will be active in the correct tissues of the recipient plant or animal.　　The creation of transgenic animals is one of the most dramatic advances derived from recombinant DNA technology. A transgenic animal results from insertion of a foreign gene into an embryo. The foreign gene becomes a permanent part of the host animals’ genetic material. As the embryo develops, the foreign gene may be present in many cells of the body, including the germ cells of the testis or the ovary. If the transgenic animal is fertile, the inserted foreign gene (transgene) will be inherited by future progeny. Thus, a transgenic animal, once created, can persist into future generations. Transgenic animals are different from animals in which foreign cells or foreign organs have been engrafted. The progeny of engrafted animals do not inherit the experimental change. The progeny of transgenic animals do.　　The techniques for creating a transgenic animal include the following: 1) picking a foreign gene, 2) placing the foreign gene in a suitable form called a “construct” which guides the insertion of the foreign gene into the animal genome and encourages its expression, and 3) injecting the construct into a single fertilized egg or at the very early embryo stage of the host animal. Much genetic engineering goes into the choice of a foreign gene and building a construct. The construct must have promoters to turn on foreign gene expression at its new site within the host animal genome. By choosing a particular promoter and splicing it in front of the foreign gene, we can encourage expression of our transgene within a specific tissue.　　One of the most important applications of transgenic animals is the development of new animal models of human disease. Transgenic animals can serve as models for many malignant tumors. Mice have been the most frequent hosts for transgenic modification, other domestic animals have also been used. One idea has been to create transgenic cows which secrete important pharmaceutical substances in their milk. Other attempts are being made to express human interferon in the milk of sheep.　　A transgenic crop plant contains a gene or genes which have been artificially inserted instead of the plant acquiring them through pollination. The inserted gene sequence (known as the transgene) may come from another unrelated plant, or from a completely different species: transgenic BT corn, for example, which produces its own insecticide, containing a gene from a bacterium. Plants containing transgenes are often called genetically modified or GM crops although in reality all crops have been genetically modified from their original wild state by domestication, selection and controlled breeding over long periods of time.

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