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When prehistoric man arrived in new parts of the world, something strange happened to the large animals. They suddenly became extinct. Smaller species survived. The large, slow-growing animals were easy game, and were quickly hunted to extinction. Now something similar could be happening in the oceans.
That the seas are being overfished has been known for years. What researchers such as Ransom Myers and Boris Worm have shown is just how fast things are changing. They have looked at half a century of data from fisheries around the world. Their methods do not attempt to estimate the actual biomass (the amount of living biological matter) of fish species in particular parts of the ocean, but rather changes in that biomass over time. According to their latest paper published in Nature, the biomass of large predators (animals that kill and eat other animals) in a new fishery is reduced on average by 80% within 15 years of the start of exploitation. In some long-fished areas, it has halved again since then.
Dr. Worm acknowledges that the figures are conservative. One reason for this is that fishing technology has improved. Today’s vessels can find their prey using satellites and sonar, which were not available 50 years ago. That means a higher proportion of what is in the sea is being caught, so the real difference between present and past is likely to be worse than the one recorded by changes in catch sizes. In the early days, too, longlines would have been more saturated with fish. Some individuals would therefore not have been caught, since no baited hooks would have been available to trap them, leading to an underestimate of fish stocks in the past. Furthermore, in the early days of longline fishing, a lot of fish were lost to sharks after they had been hooked. That is no longer a problem, because there are fewer sharks around now.
Dr. Myers and Dr. Worm argue that their work gives a correct baseline, which future management efforts must take into account. They believe the data support an idea current among marine biologists, that of the “shifting baseline.” The notion is that people have failed to detect the massive changes which have happened in the ocean because they have been looking back only a relatively short time into the past. That matters because theory suggests that the maximum sustainable yield that can be cropped from a fishery comes when the biomass of a target species is about 50% of its original levels. Most fisheries are well below that, which is a bad way to do business.
31. The extinction of large prehistoric animals is noted to suggest that ________.
[A] large animal were vulnerable to the changing environment
[B] small species survived as large animals disappeared
[C] large sea animals may face the same threat today
[D] slow-growing fish outlive fast-growing ones
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更多 “ Text 3When prehistoric man arrived in new parts of the world, something strange happened to the large animals. They suddenly became extinct. Smaller species survived. The large, slow-growing animals were easy game, and were quickly hunted to extinction. Now something similar could be happening in the oceans.That the seas are being overfished has been known for years. What researchers such as Ransom Myers and Boris Worm have shown is just how fast things are changing. They have looked at half a century of data from fisheries around the world. Their methods do not attempt to estimate the actual biomass (the amount of living biological matter) of fish species in particular parts of the ocean, but rather changes in that biomass over time. According to their latest paper published in Nature, the biomass of large predators (animals that kill and eat other animals) in a new fishery is reduced on average by 80% within 15 years of the start of exploitation. In some long-fished areas, it has halved again since then.Dr. Worm acknowledges that the figures are conservative. One reason for this is that fishing technology has improved. Today’s vessels can find their prey using satellites and sonar, which were not available 50 years ago. That means a higher proportion of what is in the sea is being caught, so the real difference between present and past is likely to be worse than the one recorded by changes in catch sizes. In the early days, too, longlines would have been more saturated with fish. Some individuals would therefore not have been caught, since no baited hooks would have been available to trap them, leading to an underestimate of fish stocks in the past. Furthermore, in the early days of longline fishing, a lot of fish were lost to sharks after they had been hooked. That is no longer a problem, because there are fewer sharks around now.Dr. Myers and Dr. Worm argue that their work gives a correct baseline, which future management efforts must take into account. They believe the data support an idea current among marine biologists, that of the “shifting baseline.” The notion is that people have failed to detect the massive changes which have happened in the ocean because they have been looking back only a relatively short time into the past. That matters because theory suggests that the maximum sustainable yield that can be cropped from a fishery comes when the biomass of a target species is about 50% of its original levels. Most fisheries are well below that, which is a bad way to do business.31. The extinction of large prehistoric animals is noted to suggest that ________.[A] large animal were vulnerable to the changing environment[B] small species survived as large animals disappeared[C] large sea animals may face the same threat today[D] slow-growing fish outlive fast-growing ones ” 相关考题
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Passage FiveJim was intelligent, but he hated hard work. He said, "You work hard, and make a lot of money, and then the government takes most of it. I want easy work that gives me lots of money and that the government doesn't know about".So he became a thief--but he did not do the stealing himself. He got others to do it. They were much less intelligent than he was, so he arranged everything and told them what to do.One day they were looking for rich families to rob, and Jim sent one of them to a large beautiful house just outside the town.It was evening, and when the man looked through one of the windows, he saw a young man and a girl playing on a piano.When he went back to Jim, he said, "That family can't have much money. Two people were playing on the same piano there."52. What Jim said can be said to be______.A. an excuseB. a lieC. a jokeD. a truth
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Passage TwoQuestions 26 to 30 are based on the following passage.Scientists have established that influenza viruses taken from man can cause the disease in animals. In addition，man can catch the disease from animals. In fact，a great number of wild birds seem to carry the virus without showing any evidence of illness. Some scientists conclude that a large family of influenza viruses may have evolved in the bird kingdom，a group that has been on the earth 100 million years and is able to carry the virus without contracting the disease. These are even convincing evidence to show that virus strains are transmitted from place to place and from continent to continent by migrating birds.It is known that two influenza viruses can recombine when both are present in an animal at the same time. The result of such recombinations is a great variety of strains constraining different H and N spikes. This raises the possibility that a human influenza virus can recombine with an influenza virus form. a lower animal to produce an entirely new spike.Research is underway to determine if that is the way that major new strains come into being. Another possibility is that two animal influenza strains may recombine in a pig，for example，to produce a new strain which is transmitted to man.According to the passage，scientists have discovered that influenza viruses______.A. cause ill health in wild birdsB. do not always cause symptoms in birdsC. are rarely present in wild birdsD. change when transferred from animals to man
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Thousands of people were gathering in the square.( )!A.What large crowdB.What a large crowdC.How large crowdD.How a large crowd
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It was amazing that they ()handling such a large order (订单).
A、were capable ofB、are able toC、have the capabilities ofD、could
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Modern zoos are very different from zoos that were built fifty years ago.At that time, zoos were places (1) people could go to see animals from many parts of the world.They animals lived in cages that were made (2) Concrete with iron bars, cages that were easy to keep clean.Unfortunately for the animals, the cages were small and impossible to hide in.the zoos environment was anything (3) natural.Al though the zoo keepers took good care of the animals and fed them well, many of the animals did not thrive: they behaved in strange ways, and they often became illIn modern zoos, people can see animals in more natural habitats.The animals are(4)more freedom in large areas so that they can live more comfortably as they would in nature Even the appearance of zoos has changed, trees and grass grow in the cages, and streams of water flow (5) the areas that animals live in.(完型填空)A.OfB.ButC.WhereD.OverE.Given
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Text 3Everyone has heard of the San Andreas fault, which constantly threatens California and the West Coast with earth- quakes. But how many people know about the equally serious New Madrid fault in Missouri.'?Between December of 1811 and February of 1812, three major earthquakes occurred, all centered around the town of New Madrid, Missouri, on the Mississippi River. Property damage was severe.Buildings in the area were almost dest oyed. Whole forests fell at once, and huge cracks opened in the ground, allowing smell of sulfur to filter upward.The Mississippi River itself completely changed character, developing sudden rapids and whirlpools. Several times it changed its course, and once, according to some observers, it actually appeared to run backwards. Few people were killed in the New Madrid earthquakes, probably simply because few people lived in the area in 1811; but the severity of the earth- quakes are shown by the fact that the shock waves rang bells in church towers in Charleston, South Carolina, on the coast. Buildings shook in New York City, and clocks were stopped in Washington D.C. Scientists now know that America's two major faults are essentially different. The San Andreas is a horizontal boundary between two major land masses that are slowly moving in opposite directions. California earthquakes result when the movement of these two masses suddenly lurches forward.The New Madrid fault, on the other hand, is a vertical fault; at some point, possibly hundreds of millions of years ago, rock was pushed up toward the surface, probably by volcanoes under the surface. Suddenly, the volcanoes cooled and the rock collapsed, leaving huge cracks. Even now', the rock continues to settle downwards, and sudden sinking motions trigger earthquakes in the region. The fault itself, a large crack in this layer of rock, with dozens of other cracks that split off from it, extends from northeast Arkansas through Missouri and into southern Illinois.Scientists who have studied the New Madrid fault say there have been numerous smaller quakes in the area since 1811; these smaller quakes indicate that larger ones are probably coming, but rite scientists say they have no method of predicting when a large earthquake will occur.31. This passage is mainly about ______.A) the New Madrid fault in MissouriB) the San Andreas and the New Madrid faultsC) the causes of faultsD) current scientific knowledge about faults
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In C language，functions are important because they provide a way to(69)code so that a large complex program can be written by combining many smaller parts．A．modifyB．modularizeC．blockD．board
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In C language, functions are important because they provide a way to ______ code so that a large complex program can be written by combining many smaller parts.A．modifyB．modularizeC．blockD．board
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BIn the 1500s，the camera was invented．However，in the early 1800s people found a way to make the pictures permanent． Even then，photography was a new field． Most families had their pictures taken by photographers．People did not own cameras because taking pictures and developing the films were too difficult．In 1884 ，George Eastman invented a kind of film．lt could be put into a small camera． The new film was easy to use． So many people began to buy cameras． When they had used up their films people returned their cameras to the factory． There，the films were developed，and pictures were made． More films were put into the cameras． And they were sent back to the owners with their pictures．Today's cameras are much easier to use． Photography has become a hot hobby， There are also many new jobs in this field，especially in news reporting． Newspapers，magazines，and tele-vision all need pictures to tell stories， Photographers help scientists by taking pictures through microscopes and telescopes． Deep-sea divers take pictures of ocean plants and animals． Astro-nauts take their cameras into space． Man finds new uses of the camera every day．( )26． When did people find a way to make the pictures permanent?A． In the 1500s．B． In the 1600s．C． In the 1700s．D． In the 1800s．
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The new large passenger jets have made the traffic problems at airports_______．A.more bad than it was
B.the worse than before
C.worse than ever before
D.more bad than they were
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New Foods and the New WorldIn the last 500 years,nothing about people—not their clothes,ideas,or languages—has changed as much as what they eat. The original chocolate drink was made from the seeds of the cocoa tree by South American Indians .The Spanish introduced it to the rest of the world during the 1500's .And although it was very expensive,it quickly became fashionable.In London,shops where chocolate drinks were served became important meeting places. Some still exist today.The potato is also from the New World. Around 1600,the Spanish brought it from Peru to Europe,where it soon was widely grown. Ireland became so dependent on it that thousands of Irish people starved when the crop failed during the“Potato Famine”of 1845—1846,and thou- sands more were forced to emigrate to America.There are many other foods that have traveled from South America to the Old World. But some others went in the opposite direction. Brazil is now the world's largest grower of coffee,and coffee is an important crop in Colombia and other South American countries.But it is native to Ethiopia. It was first made into a drink by Arabs during the 1400's.According to an Arabic legend,coffee was discovered when a person named Kaldi noticed that his goats were attracted to the red berries on a coffee bush.He tried one and experienced the “wide-awake”feeling that one-third of the world's population now starts the day with. The Arabic legend is used to prove thatA:.coffee was first discovered by KaldiB: coffee was first discovered by Kaldi's goatsC:.coffee was first discovered in south American countriesD: coffee drinks were first made by Arabs
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New Foods and the New WorldIn the last 500 years,nothing about people—not their clothes,ideas,or languages—has changed as much as what they eat. The original chocolate drink was made from the seeds of the cocoa tree by South American Indians .The Spanish introduced it to the rest of the world during the 1500's .And although it was very expensive,it quickly became fashionable.In London,shops where chocolate drinks were served became important meeting places. Some still exist today.The potato is also from the New World. Around 1600,the Spanish brought it from Peru to Europe,where it soon was widely grown. Ireland became so dependent on it that thousands of Irish people starved when the crop failed during the“Potato Famine”of 1845—1846,and thou- sands more were forced to emigrate to America.There are many other foods that have traveled from South America to the Old World. But some others went in the opposite direction. Brazil is now the world's largest grower of coffee,and coffee is an important crop in Colombia and other South American countries.But it is native to Ethiopia. It was first made into a drink by Arabs during the 1400's.According to an Arabic legend,coffee was discovered when a person named Kaldi noticed that his goats were attracted to the red berries on a coffee bush.He tried one and experienced the “wide-awake”feeling that one-third of the world's population now starts the day with. Coffee originally came from_______.A:.BrazilB: ColombiaC:EthiopiaD: Arabia
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共用题干
New Foods and the New WorldIn the last 500 years,nothing about people—not their clothes,ideas,or languages—has changed as much as what they eat. The original chocolate drink was made from the seeds of the cocoa tree by South American Indians .The Spanish introduced it to the rest of the world during the 1500's .And although it was very expensive,it quickly became fashionable.In London,shops where chocolate drinks were served became important meeting places. Some still exist today.The potato is also from the New World. Around 1600,the Spanish brought it from Peru to Europe,where it soon was widely grown. Ireland became so dependent on it that thousands of Irish people starved when the crop failed during the“Potato Famine”of 1845—1846,and thou- sands more were forced to emigrate to America.There are many other foods that have traveled from South America to the Old World. But some others went in the opposite direction. Brazil is now the world's largest grower of coffee,and coffee is an important crop in Colombia and other South American countries.But it is native to Ethiopia. It was first made into a drink by Arabs during the 1400's.According to an Arabic legend,coffee was discovered when a person named Kaldi noticed that his goats were attracted to the red berries on a coffee bush.He tried one and experienced the “wide-awake”feeling that one-third of the world's population now starts the day with. Thousands of Irish people starved during the“Potato Famine”because______.A: they were so dependent on the potato that they refused to eat anything elseB: they were forced to emigrate to AmericaC: the weather conditions in Ireland were not suitable for growing the potatoD:.the potato harvest was bad
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The Commonwealth of Nations is an association of independent countries ( ) A.that speak English as their native language
B.that have a large number of British immigrants
C.that were once colonies of Britain
D.that fought on the side of Britain in the two world wars
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Up to the end of WW II,there were（）waves of large-scale emigration to the United States.AfourBtwoCthreeDNone of the above
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The most important features in the growth of American economy in the early 20th cenruty were（）Athe use of steam and electricity as chief energy,the development of lare corporation and the development of railwayBthe development of large corporation,urbanization and the employment in production of new technologyCthe appearance of airplane,the use of electricity on a large scale and urbanizationDthe rapid development of industry,railway and large cities
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The Commonwealth of Nations is an association of independent countries（）.Athat were once colonies of BritainBthat have a large number of British immigrantsCthat have close relations with BritainDthat have fought on the side of Britain in the two world wars
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The Commonwealth of Nations is an association of independent countries（）.A、that were once colonies of BritainB、that have a large number of British immigrantsC、that have close relations with BritainD、that have fought on the side of Britain in the two world wars
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The most important features in the growth of American economy in the early 20th cenruty were（）A、the use of steam and electricity as chief energy,the development of lare corporation and the development of railwayB、the development of large corporation,urbanization and the employment in production of new technologyC、the appearance of airplane,the use of electricity on a large scale and urbanizationD、the rapid development of industry,railway and large cities
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单选题The Commonwealth of Nations is an association of independent countries（）.A
that were once colonies of BritainB
that have a large number of British immigrantsC
that have close relations with BritainD
that have fought on the side of Britain in the two world wars
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单选题The problem with Elkhorn and stag horn corals lies in that _____.A
they were not much-liked by many peopleB
they were not well-known enough to be an iconC
they were not considered animals by many peopleD
they were not added to the list of Endangered Species
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单选题The most important features in the growth of American economy in the early 20th cenruty were（）A
the use of steam and electricity as chief energy,the development of lare corporation and the development of railwayB
the development of large corporation,urbanization and the employment in production of new technologyC
the appearance of airplane,the use of electricity on a large scale and urbanizationD
the rapid development of industry,railway and large cities
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单选题A fire _____ during the night and a large number of houses _____ to ashes.A
broke out, were burntB
was broke out, were burntC
broke out, burntD
set out, were burned
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单选题What did the researchers learn from the second step?A
The trees in the new forest were in different size.B
The insects in the new forest had a different taste.C
Tamarins could get used to the new environment.D
Above 80% of tamarins survived.
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单选题A
They are harmful animals.B
They are strange animals.C
They are attractive animals.D
They are friendly animals.
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