共用题干 Black HolesMost scientists agree that black holes exist but are nearly impossible to locate.A black hole in the universe is not a solid object,like a planet,but it is shaped like a sphere（球体）. Astronomers（天文学家）think that at the center of a black hole there is a single point in space with infinite（无限的）density（稠密）.This single point is called a singularity（奇点）. If the singularity theory is correct,it means that when a massive star collapses,all the material in it disappears into the singularity.The center of a black hole would not really be a hole at all,but an infinitely dense point.Anything that crosses the black hole is pulled in by its great gravity.Although black holes do exist,they are difficult to observe.These are the reasons.No light or anything else comes out of black holes.As a result,they are invisible to a telescope.In astronomical terms,black holes are truly tiny.For example,a black hole formed by the collapse of a giant star would have an event horizon（视界）only 18 miles across.The nearest black holes would be dozens of light years away from Earth.One light year is about 6 trillion（万亿）miles. Even the most powerlul telescopes could not pick out an object so small at such a great distance.In 1994 the Hubble Space Telescope provided evidence that black holes exist.There are still answers to be found,however,so black holes remain one of the mysteries of the universe.The center of a black hole is empty.A:Right B:Wrong C:Not mentioned

考题 If the neutron star is very large(much bigger than our sun)the process of shrinking may be so intense that a black hole______(result).

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考题 There might be a massive black hole at the center of our galaxy______(swallow)up stars at a very rapid rate.

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考题 It is this information loss, connected with black hole radition,___ provides the new twist. A.whichB.thatC.whereD.it

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考题 ( ) is expert in ( ). A、The Doctor Black/ surgeryB、Doctor Black/ the surgeryC、A Doctor Black/ the surgeryD、Doctor Black/ surgery

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考题共用题干 B1i'k Holes1 Black holes can be best described as a sort of vacuum,sucking up everything in space. Scientists have discovered that black holes come from an explosion of huge stars. Stars that are near death can no longer burn due to loss of fuel , and because its temperature can no longer control the gravitational（重力的）force, hydrogen ends up putting pressure onto the star' s surface until it suddenly explodes then collapses.2 Black holes come from stars that are made of hydrogen,other gases and a few metals. When these explode it can turn into a stellar-mass ( 恒星质量）black hole , which can only occur if the star is large enough (should be bigger than the sun) for the explosion to break it into pieces,and the gravity starts to compact every piece into the tiniest particle. Try to see and compare:if a star that' s ten times the size of the sun endsup being a black hole that' s no longer than 70 kilometers ,then the Earth would become a black hole that' sonly"fraction of an inch! 3 Objects that get sucked in a black hie will always remain there,never to brsak fren. But rememberthat black holes can only gobble up（吞噬）objects within a specific distance to it It' s possible for a largestar near the sun to become a black hole,but the sun will continue to stay in place. Orbits (轨道）do notchange because the newly formed black hole, contains exactly the same amount of mass as when it was a star,only this time its mass is totally contracted that it can end up as on biggeer tnan a state. 4 So far, astronomers have figured out that black holes exist because of Albert Einstenin's theory of relativity. In the end,through numerous studies ,they have discovered that black holes truly exist. Since blackholes trap light and do not give off light,it is nearly impossible to detect black goles via a telescope. Butastronomers continue to study galaxies (银河系）,space and the solar system to understand how black holes misht evolve. It is possible that black holes can exist for millions of years,and later contribute to a biggerprocess in galaxies ,which can eventually lead to creation of new entities（实体）.Scientists also credit blackholes as helpful in learning how galaxies began to form. Paragraph 2_____________A:What Happens to the Objects Around a Black Hole?B:Is There Proof That Black Holes Really Exist? C:How Were Black Holes Named? D:What Are Different Types of Black Holes?E:What Are Black Holes Made of?F:How Are Black Holes Formed?

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考题共用题干 B1i'k Holes1 Black holes can be best described as a sort of vacuum,sucking up everything in space. Scientists have discovered that black holes come from an explosion of huge stars. Stars that are near death can no longer burn due to loss of fuel , and because its temperature can no longer control the gravitational（重力的）force, hydrogen ends up putting pressure onto the star' s surface until it suddenly explodes then collapses.2 Black holes come from stars that are made of hydrogen,other gases and a few metals. When these explode it can turn into a stellar-mass ( 恒星质量）black hole , which can only occur if the star is large enough (should be bigger than the sun) for the explosion to break it into pieces,and the gravity starts to compact every piece into the tiniest particle. Try to see and compare:if a star that' s ten times the size of the sun endsup being a black hole that' s no longer than 70 kilometers ,then the Earth would become a black hole that' sonly"fraction of an inch! 3 Objects that get sucked in a black hie will always remain there,never to brsak fren. But rememberthat black holes can only gobble up（吞噬）objects within a specific distance to it It' s possible for a largestar near the sun to become a black hole,but the sun will continue to stay in place. Orbits (轨道）do notchange because the newly formed black hole, contains exactly the same amount of mass as when it was a star,only this time its mass is totally contracted that it can end up as on biggeer tnan a state. 4 So far, astronomers have figured out that black holes exist because of Albert Einstenin's theory of relativity. In the end,through numerous studies ,they have discovered that black holes truly exist. Since blackholes trap light and do not give off light,it is nearly impossible to detect black goles via a telescope. Butastronomers continue to study galaxies (银河系）,space and the solar system to understand how black holes misht evolve. It is possible that black holes can exist for millions of years,and later contribute to a biggerprocess in galaxies ,which can eventually lead to creation of new entities（实体）.Scientists also credit blackholes as helpful in learning how galaxies began to form. Black holes are formed after_____________. A: the existence of black holesB: the creation of new entitiesC: the same amount of massD: an explosion of huge starsE: a fraction of an inchF: the tiniest narticle

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考题共用题干 B1i'k Holes1 Black holes can be best described as a sort of vacuum,sucking up everything in space. Scientists have discovered that black holes come from an explosion of huge stars. Stars that are near death can no longer burn due to loss of fuel , and because its temperature can no longer control the gravitational（重力的）force, hydrogen ends up putting pressure onto the star' s surface until it suddenly explodes then collapses.2 Black holes come from stars that are made of hydrogen,other gases and a few metals. When these explode it can turn into a stellar-mass ( 恒星质量）black hole , which can only occur if the star is large enough (should be bigger than the sun) for the explosion to break it into pieces,and the gravity starts to compact every piece into the tiniest particle. Try to see and compare:if a star that' s ten times the size of the sun endsup being a black hole that' s no longer than 70 kilometers ,then the Earth would become a black hole that' sonly"fraction of an inch! 3 Objects that get sucked in a black hie will always remain there,never to brsak fren. But rememberthat black holes can only gobble up（吞噬）objects within a specific distance to it It' s possible for a largestar near the sun to become a black hole,but the sun will continue to stay in place. Orbits (轨道）do notchange because the newly formed black hole, contains exactly the same amount of mass as when it was a star,only this time its mass is totally contracted that it can end up as on biggeer tnan a state. 4 So far, astronomers have figured out that black holes exist because of Albert Einstenin's theory of relativity. In the end,through numerous studies ,they have discovered that black holes truly exist. Since blackholes trap light and do not give off light,it is nearly impossible to detect black goles via a telescope. Butastronomers continue to study galaxies (银河系）,space and the solar system to understand how black holes misht evolve. It is possible that black holes can exist for millions of years,and later contribute to a biggerprocess in galaxies ,which can eventually lead to creation of new entities（实体）.Scientists also credit blackholes as helpful in learning how galaxies began to form. Albert Einstein's theory of relativity helps to prove____________.A: the existence of black holesB: the creation of new entitiesC: the same amount of massD: an explosion of huge starsE: a fraction of an inchF: the tiniest narticle

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考题共用题干 B1i'k Holes1 Black holes can be best described as a sort of vacuum,sucking up everything in space. Scientists have discovered that black holes come from an explosion of huge stars. Stars that are near death can no longer burn due to loss of fuel , and because its temperature can no longer control the gravitational（重力的）force, hydrogen ends up putting pressure onto the star' s surface until it suddenly explodes then collapses.2 Black holes come from stars that are made of hydrogen,other gases and a few metals. When these explode it can turn into a stellar-mass ( 恒星质量）black hole , which can only occur if the star is large enough (should be bigger than the sun) for the explosion to break it into pieces,and the gravity starts to compact every piece into the tiniest particle. Try to see and compare:if a star that' s ten times the size of the sun endsup being a black hole that' s no longer than 70 kilometers ,then the Earth would become a black hole that' sonly"fraction of an inch! 3 Objects that get sucked in a black hie will always remain there,never to brsak fren. But rememberthat black holes can only gobble up（吞噬）objects within a specific distance to it It' s possible for a largestar near the sun to become a black hole,but the sun will continue to stay in place. Orbits (轨道）do notchange because the newly formed black hole, contains exactly the same amount of mass as when it was a star,only this time its mass is totally contracted that it can end up as on biggeer tnan a state. 4 So far, astronomers have figured out that black holes exist because of Albert Einstenin's theory of relativity. In the end,through numerous studies ,they have discovered that black holes truly exist. Since blackholes trap light and do not give off light,it is nearly impossible to detect black goles via a telescope. Butastronomers continue to study galaxies (银河系）,space and the solar system to understand how black holes misht evolve. It is possible that black holes can exist for millions of years,and later contribute to a biggerprocess in galaxies ,which can eventually lead to creation of new entities（实体）.Scientists also credit blackholes as helpful in learning how galaxies began to form. A newly formed black hole and the star it comes from are of____________.A: the existence of black holesB: the creation of new entitiesC: the same amount of massD: an explosion of huge starsE: a fraction of an inchF: the tiniest narticle

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考题 Light rays are turned aside by the intense gravitational field surrounding a black hole.A:heightened B:deflected C:rotated D:created

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考题共用题干 Black Holes1 Black holes can be best described as a sort of vacuum,sucking up everything in space.Scientists have discovered that black holes come from an explosion of huge stars.Stars that are near death can no longer burn due to loss of fuel , and because its temperature can no longer control the gravitational（重力的）force,hydrogen ends up putting pressure onto the star's surface until it suddenly explodes then collapses.2 Black holes come from stars ihat are made of hydrogen,other gases and a few metals.When these explode it can turn into a stellar-mass（恒星质量) black hole , which can only occur if the star is large enough (should be bigger than the sun)for the explosion to break it into pieces,and the gravity starts to compact every piece into the tiniest particle.Try to see and compare:if a star that's ten times the size of the sun ends up being a black hole that's no longer than 70 kilometers,then the Earth would become a black hole that'S only a fraction of an inch!3 Objects that get sucked in a black hole will always remain there,never to break free.i1it remember that black holes can only gobble up（吞噬）objects within a specific distance to it.It's possible for a large star near the sun to become a black hole,but the sun will continue to stay in place.Orbits（轨道）do not change because the newly formed black hole contains exactly the same amount of mass as when it was a star, only this time its mass is totally contracted that it can end up as no bigger than a state.4 Sofar,astronomers have figured out that black holes exist because of Albert Einstcin's theory of relativity.In the end,through numerous studies,they have discovered that black holes truly exist.Since black holes trap light and do not give off light,it is nearly impossible to detect black holes via a telescope.But astronomers continue to study galaxies（银河系）, space and the solar system to understand how black holes might evolve.It is possible that black holes can exist for millions of years,and later contribute to a bigger process in galaxies,which can eventually lead to creation of new entities（实体）.Scientists also credit black holes as helpful in learning how galaxies began to form.When a large star explodes,the gravity compacts every piece into______.A:the existence of black holesB:the creation of new entitiesC:the same amount of massD:an fraction of an inchE:a fraction of an inchF:the tiniest particle

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考题共用题干 Black Holes1 Black holes can be best described as a sort of vacuum,sucking up everything in space.Scientists have discovered that black holes come from an explosion of huge stars.Stars that are near death can no longer burn due to loss of fuel , and because its temperature can no longer control the gravitational（重力的）force,hydrogen ends up putting pressure onto the star's surface until it suddenly explodes then collapses.2 Black holes come from stars ihat are made of hydrogen,other gases and a few metals.When these explode it can turn into a stellar-mass（恒星质量) black hole , which can only occur if the star is large enough (should be bigger than the sun)for the explosion to break it into pieces,and the gravity starts to compact every piece into the tiniest particle.Try to see and compare:if a star that's ten times the size of the sun ends up being a black hole that's no longer than 70 kilometers,then the Earth would become a black hole that'S only a fraction of an inch!3 Objects that get sucked in a black hole will always remain there,never to break free.i1it remember that black holes can only gobble up（吞噬）objects within a specific distance to it.It's possible for a large star near the sun to become a black hole,but the sun will continue to stay in place.Orbits（轨道）do not change because the newly formed black hole contains exactly the same amount of mass as when it was a star, only this time its mass is totally contracted that it can end up as no bigger than a state.4 Sofar,astronomers have figured out that black holes exist because of Albert Einstcin's theory of relativity.In the end,through numerous studies,they have discovered that black holes truly exist.Since black holes trap light and do not give off light,it is nearly impossible to detect black holes via a telescope.But astronomers continue to study galaxies（银河系）, space and the solar system to understand how black holes might evolve.It is possible that black holes can exist for millions of years,and later contribute to a bigger process in galaxies,which can eventually lead to creation of new entities（实体）.Scientists also credit black holes as helpful in learning how galaxies began to form.Black holes are formed after_________.A:the existence of black holesB:the creation of new entitiesC:the same amount of massD:an fraction of an inchE:a fraction of an inchF:the tiniest particle

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考题共用题干 Black Holes1 Black holes can be best described as a sort of vacuum,sucking up everything in space.Scientists have discovered that black holes come from an explosion of huge stars.Stars that are near death can no longer burn due to loss of fuel , and because its temperature can no longer control the gravitational（重力的）force,hydrogen ends up putting pressure onto the star's surface until it suddenly explodes then collapses.2 Black holes come from stars ihat are made of hydrogen,other gases and a few metals.When these explode it can turn into a stellar-mass（恒星质量) black hole , which can only occur if the star is large enough (should be bigger than the sun)for the explosion to break it into pieces,and the gravity starts to compact every piece into the tiniest particle.Try to see and compare:if a star that's ten times the size of the sun ends up being a black hole that's no longer than 70 kilometers,then the Earth would become a black hole that'S only a fraction of an inch!3 Objects that get sucked in a black hole will always remain there,never to break free.i1it remember that black holes can only gobble up（吞噬）objects within a specific distance to it.It's possible for a large star near the sun to become a black hole,but the sun will continue to stay in place.Orbits（轨道）do not change because the newly formed black hole contains exactly the same amount of mass as when it was a star, only this time its mass is totally contracted that it can end up as no bigger than a state.4 Sofar,astronomers have figured out that black holes exist because of Albert Einstcin's theory of relativity.In the end,through numerous studies,they have discovered that black holes truly exist.Since black holes trap light and do not give off light,it is nearly impossible to detect black holes via a telescope.But astronomers continue to study galaxies（银河系）, space and the solar system to understand how black holes might evolve.It is possible that black holes can exist for millions of years,and later contribute to a bigger process in galaxies,which can eventually lead to creation of new entities（实体）.Scientists also credit black holes as helpful in learning how galaxies began to form.A newly formed black hole and the star it comes from are of__________.A:the existence of black holesB:the creation of new entitiesC:the same amount of massD:an fraction of an inchE:a fraction of an inchF:the tiniest particle

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考题共用题干 Black Holes1 Black holes can be best described as a sort of vacuum,sucking up everything in space.Scientists have discovered that black holes come from an explosion of huge stars.Stars that are near death can no longer burn due to loss of fuel , and because its temperature can no longer control the gravitational（重力的）force,hydrogen ends up putting pressure onto the star's surface until it suddenly explodes then collapses.2 Black holes come from stars ihat are made of hydrogen,other gases and a few metals.When these explode it can turn into a stellar-mass（恒星质量) black hole , which can only occur if the star is large enough (should be bigger than the sun)for the explosion to break it into pieces,and the gravity starts to compact every piece into the tiniest particle.Try to see and compare:if a star that's ten times the size of the sun ends up being a black hole that's no longer than 70 kilometers,then the Earth would become a black hole that'S only a fraction of an inch!3 Objects that get sucked in a black hole will always remain there,never to break free.i1it remember that black holes can only gobble up（吞噬）objects within a specific distance to it.It's possible for a large star near the sun to become a black hole,but the sun will continue to stay in place.Orbits（轨道）do not change because the newly formed black hole contains exactly the same amount of mass as when it was a star, only this time its mass is totally contracted that it can end up as no bigger than a state.4 Sofar,astronomers have figured out that black holes exist because of Albert Einstcin's theory of relativity.In the end,through numerous studies,they have discovered that black holes truly exist.Since black holes trap light and do not give off light,it is nearly impossible to detect black holes via a telescope.But astronomers continue to study galaxies（银河系）, space and the solar system to understand how black holes might evolve.It is possible that black holes can exist for millions of years,and later contribute to a bigger process in galaxies,which can eventually lead to creation of new entities（实体）.Scientists also credit black holes as helpful in learning how galaxies began to form.Paragraph 1________A:What Happens to the Objects Around a Black Hole?B:Is There Proof That Black Holes Really Exist?C:How Were Black Holes Named?D:What Are Different Types of Black Holes?E:What Are Black Holes Made of? F: How Are Black Holes Formed?

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考题 The traffic lights were red when the driver reached them．To the surprise of his passenger,the ear did not slow down．Unexpectedly the passenger was thrown forward in the vehicle as the driver put on his brakes at the last moment．The car stopped just in time. "Sorry,I didn't notice the light．I thought it was green until I saw that it was the top light which was shining." This strange story is quite true．About ten men in every hundred are color blind in some way;women are luckier--only about one in two hundred suffers from color blindness. In some cases,a man may not be able to see deep red．He may think that red,orange and yellow are all the same as green. People often like one color more than others．Blue is the color of the sky and sea．Green makes us think of fields and trees．Red is the color of blood and makes some people think of danger．Black is the color of night．In the dark we cannot see what is around us so we are sometimes afraid of the unknown and do not like black as a color. According to the passage,which of the following statements is true?A.Black stands for unhappines B.Black makes people think of nigh C.Black makes people think of sorro D.Black is the color of the mournin

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考题 Black Holes Trigger Stars to Self-Destruct 　　Scientists have long understood that supermassive black holes weighing millions or billions of suns can tear apart stars that come too close. The black hotels gravity pulls harder on the nearest part of the star, an imbalance that pulls the star apart over a period of minutes or hours, once it gets close enough. 　　Scientists say this Uneven pulling is not the only hazard facing the star. The strain of these unbalanced forces can also trigger a nuclear explosion powerful enough to destroy the star from within. Matthieu Brassart and Jean-Pierre Luminet of the Observatoire de Paris in Meudon, France, carried out computer simulations of the final moments of such an unfortunate star's life,as it veered towards a supermassive black hole. 　　When the star gets close enough, the uneven forces flatten it into a pancake shape. Some previous studies had suggested this flattening would increase the density and temperature inside the star enough to trigger intense nuclear reactions that would tear it apart. But other studies had suggested that the picture would be complicated by shock waves generated during the flattening process and that no nuclear explosion should occur. 　　The new simulations investigated the effects of shock waves in detail,and found that even when their effects are included,the conditions favor a nuclear explosion. "There will be an explosion of the star-it will be completely destroyed," Brassart says. Although the explosion obliterates the star, it saves some of the star's matter from being devoured by the black hole. The explosion is powerful enough to hurl much of the star's matter out of the black hole's reach, he says. 　　The devouring of stars by black holes may already have been observed, although at a much later stage. It is thought that several months after the event that rips the star apart,its matter starts swirling into the hole itself. It heats up as it does so, releasing ultraviolet light and X-rays. 　　If stars disrupted near black holes really do explode, then they could in principle allow these events to be detected at a much earlier stage, says Jules Hatpern of Columbia University in New York, US. "It may make it possible to see the disruption of that star immediately if it gets hot enough," he says. 　　Brassart agrees. "Perhaps it can be observed in the X-rays and gamma rays, but it's something that needs to be more studied," he says. Supernova researcher Chris Fryer of the Los Alamos National Laboratory in Los Alamos, New Mexico, US, says the deaths of these stars are difficult to simulate, and he is not sure whether the researchers have proven their case that they explode in the process. 文章(36~40) Something destructive could happen to a star that gets too close to a black hole. Which of the following destructive statements is NOT mentioned in the passage?A. The black hole could tear apart the star. B. The black hole could trigger a nuclear explosion in the star. C. The black hole could dwindle its size considerably. D. The black hole could devour the star.

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考题 According to the fourth paragraph, which of the following is NOT true?A. No nuclear explosion would be triggered inside the star. B. The star would be destroyed completely. C. Much of the star's matter thrown by the explosion would be beyond the black hole's reach. D. The black hole would completely devour the star.

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考题 What will happen several months after the explosion of the star?A. The star's matter will move further away from by the black hole. B. The black hole’s matter will heat up. C. The torn star's matter will swirl into the black hole. D. The black hole's matter will release ultraviolet light and X-rays.

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考题共用题干 Black HolesMost scientists agree that black holes exist but are nearly impossible to locate.A black hole in the universe is not a solid object, like a planet, but it is shaped like a sphere（球体）. Astronomers（天文学家）think that at the center of a black hole there is a single point in space with infinite（无限的）density（稠密）.This single point is called a singularity（奇点）.If the singularity theory is correct,it means that when a massive star collapses,all the material in it disappears into the singularity.The center of a black hole would not really be a hole at all,but an infinitely dense point.Anything that crosses the black hole is pulled in by its great gravity.Although black holes do exist,they are difficult to observe.These are the reasons.No light or anything else comes out of black holes.As a result,they are invisible to a telescope.In astronomical terms,black holes are truly tiny.For example,a black hole formed by the collapse of a giant star would have an event horizon（视界）only 18 miles across.The nearest black holes would be dozens of light years away from Earth.One light year is about 6 trillion（万亿）miles. Even the most powerful telescopes could not pick out an object so small at such a great distance.In 1994 the Hubble Space Telescope provided evidence that black holes exist. There are still answers to be found,however,so black holes remain one of the mysteries of the universe.Black holes are part of space.A:Right B:Wrong C:Not mentioned

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考题共用题干 Black HolesMost scientists agree that black holes exist but are nearly impossible to locate.A black hole in the universe is not a solid object, like a planet, but it is shaped like a sphere（球体）. Astronomers（天文学家）think that at the center of a black hole there is a single point in space with infinite（无限的）density（稠密）.This single point is called a singularity（奇点）.If the singularity theory is correct,it means that when a massive star collapses,all the material in it disappears into the singularity.The center of a black hole would not really be a hole at all,but an infinitely dense point.Anything that crosses the black hole is pulled in by its great gravity.Although black holes do exist,they are difficult to observe.These are the reasons.No light or anything else comes out of black holes.As a result,they are invisible to a telescope.In astronomical terms,black holes are truly tiny.For example,a black hole formed by the collapse of a giant star would have an event horizon（视界）only 18 miles across.The nearest black holes would be dozens of light years away from Earth.One light year is about 6 trillion（万亿）miles. Even the most powerful telescopes could not pick out an object so small at such a great distance.In 1994 the Hubble Space Telescope provided evidence that black holes exist. There are still answers to be found,however,so black holes remain one of the mysteries of the universe.The Hubble Space Telescope helps scientists to understand the nature of the universe.A:Right B:Wrong C:Not mentioned

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考题共用题干 Black HolesMost scientists agree that black holes exist but are nearly impossible to locate.A black hole in the universe is not a solid object, like a planet, but it is shaped like a sphere（球体）. Astronomers（天文学家）think that at the center of a black hole there is a single point in space with infinite（无限的）density（稠密）.This single point is called a singularity（奇点）.If the singularity theory is correct,it means that when a massive star collapses,all the material in it disappears into the singularity.The center of a black hole would not really be a hole at all,but an infinitely dense point.Anything that crosses the black hole is pulled in by its great gravity.Although black holes do exist,they are difficult to observe.These are the reasons.No light or anything else comes out of black holes.As a result,they are invisible to a telescope.In astronomical terms,black holes are truly tiny.For example,a black hole formed by the collapse of a giant star would have an event horizon（视界）only 18 miles across.The nearest black holes would be dozens of light years away from Earth.One light year is about 6 trillion（万亿）miles. Even the most powerful telescopes could not pick out an object so small at such a great distance.In 1994 the Hubble Space Telescope provided evidence that black holes exist. There are still answers to be found,however,so black holes remain one of the mysteries of the universe.The center of a black hole is empty.A:Right B:Wrong C:Not mentioned

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考题共用题干 Black HolesMost scientists agree that black holes exist but are nearly impossible to locate.A black hole in the universe is not a solid object, like a planet, but it is shaped like a sphere（球体）. Astronomers（天文学家）think that at the center of a black hole there is a single point in space with infinite（无限的）density（稠密）.This single point is called a singularity（奇点）.If the singularity theory is correct,it means that when a massive star collapses,all the material in it disappears into the singularity.The center of a black hole would not really be a hole at all,but an infinitely dense point.Anything that crosses the black hole is pulled in by its great gravity.Although black holes do exist,they are difficult to observe.These are the reasons.No light or anything else comes out of black holes.As a result,they are invisible to a telescope.In astronomical terms,black holes are truly tiny.For example,a black hole formed by the collapse of a giant star would have an event horizon（视界）only 18 miles across.The nearest black holes would be dozens of light years away from Earth.One light year is about 6 trillion（万亿）miles. Even the most powerful telescopes could not pick out an object so small at such a great distance.In 1994 the Hubble Space Telescope provided evidence that black holes exist. There are still answers to be found,however,so black holes remain one of the mysteries of the universe.The sun is the heaviest star in the universe.A:Right B:Wrong C:Not mentioned

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考题共用题干 Black HolesMost scientists agree that black holes exist but are nearly impossible to locate.A black hole in the universe is not a solid object, like a planet, but it is shaped like a sphere（球体）. Astronomers（天文学家）think that at the center of a black hole there is a single point in space with infinite（无限的）density（稠密）.This single point is called a singularity（奇点）.If the singularity theory is correct,it means that when a massive star collapses,all the material in it disappears into the singularity.The center of a black hole would not really be a hole at all,but an infinitely dense point.Anything that crosses the black hole is pulled in by its great gravity.Although black holes do exist,they are difficult to observe.These are the reasons.No light or anything else comes out of black holes.As a result,they are invisible to a telescope.In astronomical terms,black holes are truly tiny.For example,a black hole formed by the collapse of a giant star would have an event horizon（视界）only 18 miles across.The nearest black holes would be dozens of light years away from Earth.One light year is about 6 trillion（万亿）miles. Even the most powerful telescopes could not pick out an object so small at such a great distance.In 1994 the Hubble Space Telescope provided evidence that black holes exist. There are still answers to be found,however,so black holes remain one of the mysteries of the universe.Black holes exist but are difficult to observe.A:Right B:Wrong C:Not mentioned

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考题共用题干 Black HolesMost scientists agree that black holes exist but are nearly impossible to locate.A black hole in the universe is not a solid object, like a planet, but it is shaped like a sphere（球体）. Astronomers（天文学家）think that at the center of a black hole there is a single point in space with infinite（无限的）density（稠密）.This single point is called a singularity（奇点）.If the singularity theory is correct,it means that when a massive star collapses,all the material in it disappears into the singularity.The center of a black hole would not really be a hole at all,but an infinitely dense point.Anything that crosses the black hole is pulled in by its great gravity.Although black holes do exist,they are difficult to observe.These are the reasons.No light or anything else comes out of black holes.As a result,they are invisible to a telescope.In astronomical terms,black holes are truly tiny.For example,a black hole formed by the collapse of a giant star would have an event horizon（视界）only 18 miles across.The nearest black holes would be dozens of light years away from Earth.One light year is about 6 trillion（万亿）miles. Even the most powerful telescopes could not pick out an object so small at such a great distance.In 1994 the Hubble Space Telescope provided evidence that black holes exist. There are still answers to be found,however,so black holes remain one of the mysteries of the universe.The attraction of two large stars leads to gravity.A:Right B:Wrong C:Not mentioned

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考题 Which statement about Remotely Triggered Black Hole （RTBH） is true？（）A、Route tagging is one of the techniques used by RTBHB、It is used for BGP authenticationC、It cannot work with static routesD、It uses extended ACLs for blocking attacks by creating a black holeE、Before configuring RTBH LDP must be enabled on the interface

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考题 Which of the following are steps to configure destination-based Remote Triggered Black Hole（RTBH）filtering？（）A、Configure OSPF between trigger router and black hole routesB、Configure all edge routers with static （reserved） host route to Null0C、Configure BGP beteen trigger and black hole routersD、Configure on trigger router to advertise victim host route with commumityE、Activate black hole by redistributing route for victim into BGP with next-hop set to the static（reserved）host route configured on edge routers

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考题 What is the requirement of Remote Triggered Black Hole （RTBH ） filtering？（）A、IBGP updates exchange between trigger router and black hole routerB、EBGP updates exchange between trigger router and black hole routerC、OSPF updates exchange between trigger router and black hole routerD、ISIS updates exchange between trigger router and black hole router

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考题单选题According to the passage, which of the following statements is NOT TRUE?A Marley Dias is a black girl.B Marley Dias doesn't like reading.C Marley Dias wants to become an editor in the future.D Movies seldom represent black people in positive ways.

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考题单选题Which statement about Remotely Triggered Black Hole （RTBH） is true？（）A Route tagging is one of the techniques used by RTBHB It is used for BGP authenticationC It cannot work with static routesD It uses extended ACLs for blocking attacks by creating a black holeE Before configuring RTBH LDP must be enabled on the interface

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