单选题For hundreds of years, pearl divers have gathered pearls directly from mollusks on the seafloor. This is an extremely risky profession, exposing the divers to risks of drowning, air embolism, and shark attacks. Still, as long as society demands authentic cultured pearls, these brave divers must continue to risk their lives. Which of the following statements, if true, most seriously weakens the conclusion above?AShark attacks on pearl divers have decreased steadily over the last three decades because of declining shark populations.BCultured pearls are generally considered more beautiful than those made by artificial means.CRobotic pearl harvesters can gather pearls faster and at less cost than human divers, although they may disturb aquatic communities.DPart of the value of cultured pearls derives from the exotic way in which they are obtained.EWith the proper equipment and training, a diver employing scuba gear can harvest three times as many pearls per hour as can a free air diver.
单选题
For hundreds of years, pearl divers have gathered pearls directly from mollusks on the seafloor. This is an extremely risky profession, exposing the divers to risks of drowning, air embolism, and shark attacks. Still, as long as society demands authentic cultured pearls, these brave divers must continue to risk their lives. Which of the following statements, if true, most seriously weakens the conclusion above?
A
Shark attacks on pearl divers have decreased steadily over the last three decades because of declining shark populations.
B
Cultured pearls are generally considered more beautiful than those made by artificial means.
C
Robotic pearl harvesters can gather pearls faster and at less cost than human divers, although they may disturb aquatic communities.
D
Part of the value of cultured pearls derives from the exotic way in which they are obtained.
E
With the proper equipment and training, a diver employing scuba gear can harvest three times as many pearls per hour as can a free air diver.
参考解析
解析：
C选项提供了采集珍珠的另一种方式，削弱了潜水员必须冒险采集珍珠这一结论，故本题选C项。
C选项提供了采集珍珠的另一种方式，削弱了潜水员必须冒险采集珍珠这一结论，故本题选C项。
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The journey two divers(潜水员)made some time ago to the very deepest point on the earth make us realize how much of the world still remains to be studied. The two men went down seven miles to the bottom of the Pacific Ocean inside a small ball to find out if there are any ocean currents(水流)or signs of life.It was necessary to set out early, so that the ball would come to the surface in daylight, and so be easily found by the mother ship which would be waiting for it. The divers began preparations(准备)early in the morning and soon afterwards, when all was ready, the steel ball disappeared under the surface of the water.The divers felt as if they were going down steps as they passed through warm and cold layers(层)of water. In time, the temperature dropped to freezing point. They kept in touch with the mother ship by telephone telling how they felt. Then, at a depth(深度)of 3,000 feet, the telephone stopped working and they were quite cut off from the outside world. All went well until some four hours later at 30,000 feet, the men were frightened by a loud, cracking(爆裂)noise: even the smallest hole in the ball would have meant instant death. Luckily, though, it was only one of the outer(外部的)windows that had broken. Soon afterwards, the ball touched the soft ocean floor raising a big cloud of "dust" made up of small dead sea-creatures. Here, powerful lights lit up the dark water and the men were surprised to see fish swimming just above them quite untroubled by the great water pressure(压力). But they did not dare to leave the lights on for long , as the heat from them made the water boil. Quite unexpectedly, the telephone began working again and the faint(微弱的)but clear voices of the divers were heard on the mother ship seven miles away. After a stay of thirty minutes the men began their journey up, arriving three hours later, cold and wet through, but none the worse for their experience.1. The purpose of the diver's journey to the deepest point on the earth was to find _____.A. if there are water currents and life in the great depthsB. if people can stand the severe cold in the great depthsC. if there are steps in the great depthsD. if the telephone works well in the great depths2. The divers set out early in the morning so that _____.A. they could return to the surface during the dayB. they could see at the bottom of the oceanC. they could avoid the cold at nightD. they could stay long at the bottom3. Which of the following statements is true?A. The ocean water temperature decreases steadily with the depthB. There are steps on the way to the bottom of the Pacific OceanC. There are steps between the water layers of different temperatureD. The water layers of different temperatures made the divers feel as if they were going down steps4. As the divers went down to the ocean floor, the telephone _____.A. kept working all the timeB. stopped working at a depth of 3,000 feet and began working again after they reached the bottomC. stopped working at a depth of 3,000 feet and began working at 30,000 feetD. stopped working at a depth of 3,000 feet and began working again when they returned to the same depth5. On the ocean floor, the divers found that _____.A. there was no life but some small dead sea-creaturesB. fish were swimming as freely as they do near the surfaceC. fish were not swimming freely in the dark waterD. fish were not swimming freely under the high water pressure
Text 3Under certain circumstances, the human body must cope with gases at greater-than-normal atmospheric pressure. For example, gas pressures increase rapidly during a dive made with scuba gear because the breathing equipment allows divers to stay underwater longer and dive deeper.The pressure exerted on the human body increases by 1 atmosphere for every 10 meters of depth in seawater, so that at 30 meters in seawater a diver is exposed to a pressure of about 4 atmospheres. The pressure of the gases being breathed must equal the external pressure applied to the body, otherwise breathing is very difficult. Therefore all of the gases in the air breathed by a scuba diver at 40 meters are present at five times their usual pressure. Nitrogen, which composes 80 per cent of the air we breathe, usually causes a balmy feeling of well-being at this pressure. At a depth of 5 atmospheres, nitrogen causes symptoms resembling alcohol intoxication, known as nitrogen narcosis. Nitrogen narcosis apparently results from a direct effect on the brain of the large amounts of nitrogen cause under these pressurized helium does not exert a similar narcotic effect.As a scuba diver descends, the pressure of nitrogen in the lungs increases. Nitrogen then diffuses from the lungs to the blood, and from the blood to body tissues. The reverse occurs when the diver surfaces; the nitrogen pressure in the lungs falls and the nitrogen diffuses from the tissues into the blood, and from the blood into the lungs. If the return to the surface is too rapid, nitrogen in the tissues and blood cannot diffuse out rapidly enough and nitrogen bubbles are formed. They can cause severe pains, particularly around the joints.Another complication may result if the breath is held during ascent. During ascent from a depth of 10 meters, the volume of air in the lungs will double because the air pressure at the surface is only half of what it was at 10 meters. This change in volume may cause the lungs to distend and even rupture. This condition is called air embolism. To avoid this event, a diver must ascend slowly, never at a rate exceeding the rise of the exhaled air bubbles, and must exhale during as- cent.31. What does the passage mainly discuss?A) The equipment divers use.B) The effects of pressure on gases in the human body.C) How to prepare for a deep dive.D) The symptoms of nitrogen bubbles in the bloodstream.
It can be inferred from the passage that which of the following presents the greatest danger to diver?A) Pressurized helium.B) Nitrogen diffusion.C) Nitrogen bubbles.D) An air embolism.
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共用题干Science Fiction1 Amongst the most popular books being written today are those which are usually classified as science fiction.Hundreds of titles are published every year and are read by all kinds of people.Furthermore,some of the most successful films of recent years have been based on science fiction stories.2 It is often thought that science fiction is a fairly new development in literature,but its ancestors can be found in books written hundreds of years ago.These books were often concerned with the presentation of some form of ideal society,a theme which is still often found in modern stories.3 Most of the classics of science fiction,however,have been written within the last hundred years. Books by writers such as Jules Verne and H.G.Wells,to mention just two well-known authors,have been translated into many languages.4 Modern science fiction writers don ' t write about men from Mars（火星）or space adventure stories. They are more interested in predicting the results of technical developments on society and the human mind; or in imagining future worlds which are a reflection of the world which we live in now.Because of this,their writing has obvious political undertones（含义）.5 In an age where science fact frequently overtakes（超过）science fiction , the writers may find it difficult to keep ahead of scientific advances.Those who are sufficiently clear-sighted to see the way we are going,however,may provide a valuable lesson on how to deal with the problems which society will inevitably face as it tries to master its new technology.The writers find it difficult______.A:concerned with the problems to solve in the futureB:to keep ahead of scientific advancesC:have political implicationD:a current themeE:read worldwideF:a reciirrent theme
共用题干Science Fiction1 Amongst the most popular books being written today are those which are usually classified as science fiction.Hundreds of titles are published every year and are read by all kinds of people.Furthermore,some of the most successful films of recent years have been based on science fiction stories.2 It is often thought that science fiction is a fairly new development in literature,but its ancestors can be found in books written hundreds of years ago.These books were often concerned with the presentation of some form of ideal society,a theme which is still often found in modern stories.3 Most of the classics of science fiction,however,have been written within the last hundred years. Books by writers such as Jules Verne and H.G.Wells,to mention just two well-known authors,have been translated into many languages.4 Modern science fiction writers don ' t write about men from Mars（火星）or space adventure stories. They are more interested in predicting the results of technical developments on society and the human mind; or in imagining future worlds which are a reflection of the world which we live in now.Because of this,their writing has obvious political undertones（含义）.5 In an age where science fact frequently overtakes（超过）science fiction , the writers may find it difficult to keep ahead of scientific advances.Those who are sufficiently clear-sighted to see the way we are going,however,may provide a valuable lesson on how to deal with the problems which society will inevitably face as it tries to master its new technology.Some form of ideal society is______.A:concerned with the problems to solve in the futureB:to keep ahead of scientific advancesC:have political implicationD:a current themeE:read worldwideF:a reciirrent theme
They have given up the hope to save their friend from drowning.A:.endedB:abandonedC:builtD:strengthen
Deep inside a mountain near Sweetwater in East Tennessee is a bady?of water known as the Lost?Sea.It is listed by the Guinness Book of World Records as the world′s largest underground lake.The Lost Sea is part of an extensive and historic cave system called Craighead Caverns.The caverns have been known and used since the days of the Cherokee Indian nation.The cave?expands into a series of huge rooms from a small opening on the side of the mountain.Approximately?one mile from the entrance,in a room called-The Council Room",many Indian artifacts have been?found.Some of the items discovered include pottery,arrowheads,weapons,and jewelry.For many years there were persistent rumors of a large underground lake somewhere in a cave,but it was not discovered until 1905.In that year,a thirteen-year-old boy named Ben Sands crawled through a small opening three hundred feet underground.:He found himself in a large cave half filled?with water.Today tourists visit the Lost Sea and ride far out onto it in glass-bottomed boats powered by electric motors.More than thirteen acres of water have been mapped out so far and still no end to the lake has been found.Even though teams of divers have tried to explore the Lost Sea,the full extentof it is still unknown.What was found in"The Council Room"?A.A small natural opening.B.A large cave.C.Another series of rooms.D.Many old Indian objects.
Deep inside a mountain near Sweetwater in East Tennessee is a bady?of water known as the Lost?Sea.It is listed by the Guinness Book of World Records as the world′s largest underground lake.The Lost Sea is part of an extensive and historic cave system called Craighead Caverns.The caverns have been known and used since the days of the Cherokee Indian nation.The cave?expands into a series of huge rooms from a small opening on the side of the mountain.Approximately?one mile from the entrance,in a room called-The Council Room",many Indian artifacts have been?found.Some of the items discovered include pottery,arrowheads,weapons,and jewelry.For many years there were persistent rumors of a large underground lake somewhere in a cave,but it was not discovered until 1905.In that year,a thirteen-year-old boy named Ben Sands crawled through a small opening three hundred feet underground.:He found himself in a large cave half filled?with water.Today tourists visit the Lost Sea and ride far out onto it in glass-bottomed boats powered by electric motors.More than thirteen acres of water have been mapped out so far and still no end to the lake has been found.Even though teams of divers have tried to explore the Lost Sea,the full extentof it is still unknown.It can be inferred from the passage that the Craighead Caverns presently serve as__________.A.an underground testing siteB.an Indian meeting groundC.a tourist attractionD.a motor boat race course
Among the most popular books being written today are those which are usually classified as science fiction. Hundreds of titles are published every year and are read by all kinds of people.Furthermore, some of the most successful films in recent years have been based on science fiction stories.It is often thought that science fiction is a fairly new development in literature, but it can be found in books written hundreds of years ago. These books were often concerned with the presentation of some form of ideal society, a theme which is still often found in modern stories.Most of the classics of science fiction, however, have been written within the last hundred years. Books by writers such as Jules Verne and H.G. Wells, to mention just two well-knownauthors, have been translated into many languages. Modern science fiction writers don't write about men from Mars or space adventure stories. They are more interested in predicting the results of technical developments on society and the human mind; or in imagining future world which are a reflection of the world which we live in now. Because of this their writing has obviously political undertones.In an age where science fact frequently overtakes science fiction, the writers may find it difficult to keep ahead of scientific advances. Those who are sufficiently clear-sighted to see the way we are going, however, may provide a valuable lesson on how to deal with the problems which society will inevitably face as it tries to master its new technology.In the past, science fiction was probably concerned with查看材料A.men from Mars or space adventures storiesB.prediction the results of technical developments on societyC.predicting the human mindD.imagining future worlds which are a reflection of the modern world
Among the most popular books being written today are those which are usually classified as science fiction. Hundreds of titles are published every year and are read by all kinds of people.Furthermore, some of the most successful films in recent years have been based on science fiction stories.It is often thought that science fiction is a fairly new development in literature, but it can be found in books written hundreds of years ago. These books were often concerned with the presentation of some form of ideal society, a theme which is still often found in modern stories.Most of the classics of science fiction, however, have been written within the last hundred years. Books by writers such as Jules Verne and H.G. Wells, to mention just two well-knownauthors, have been translated into many languages. Modern science fiction writers don't write about men from Mars or space adventure stories. They are more interested in predicting the results of technical developments on society and the human mind; or in imagining future world which are a reflection of the world which we live in now. Because of this their writing has obviously political undertones.In an age where science fact frequently overtakes science fiction, the writers may find it difficult to keep ahead of scientific advances. Those who are sufficiently clear-sighted to see the way we are going, however, may provide a valuable lesson on how to deal with the problems which society will inevitably face as it tries to master its new technology.Which of the following statements can't prove that science fiction is very popular today 查看材料A.Hundreds of titles are published every year.B.All kinds of people love it.C.Some of the most successful films of recent years have been based on science fiction stories.D.Science fiction can be found in books written hundreds of years ago.
Among the most popular books being written today are those which are usually classified as science fiction. Hundreds of titles are published every year and are read by all kinds of people.Furthermore, some of the most successful films in recent years have been based on science fiction stories.It is often thought that science fiction is a fairly new development in literature, but it can be found in books written hundreds of years ago. These books were often concerned with the presentation of some form of ideal society, a theme which is still often found in modern stories.Most of the classics of science fiction, however, have been written within the last hundred years. Books by writers such as Jules Verne and H.G. Wells, to mention just two well-knownauthors, have been translated into many languages. Modern science fiction writers don't write about men from Mars or space adventure stories. They are more interested in predicting the results of technical developments on society and the human mind; or in imagining future world which are a reflection of the world which we live in now. Because of this their writing has obviously political undertones.In an age where science fact frequently overtakes science fiction, the writers may find it difficult to keep ahead of scientific advances. Those who are sufficiently clear-sighted to see the way we are going, however, may provide a valuable lesson on how to deal with the problems which society will inevitably face as it tries to master its new technology.The best title of the passage may probably be查看材料A.Science FictionB.The Popularity of Science FictionC.The Origin of Science FictionD.The Themes of Science Fiction
The Craighead Caverns have been known________.A.through historyB.since the time of the Indian nationsC.since 1905D.since divers explored them
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