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 authent

题目
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.

相似考题

1.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

2.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.

3.Steam smoke will occur when ______.A.extremely cold air from shore passes over warmer waterB.warm dry air from shore passes over cooler waterC.cold ocean water evaporates into warm airD.cool rain passes through a warm air mass

4.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.

参考答案和解析
正确答案： E
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。
更多“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 authent”相关问题

  • 第1题：

    共用题干
    Science Fiction
    1 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 future
    B:to keep ahead of scientific advances
    C:have political implication
    D:a current theme
    E:read worldwide
    F:a reciirrent theme

    答案：B
    解析：
    第二段第一句提到，人们常认为科幻小说是文学中的新生产物，然而在几百年前所写的书中就能发现科幻小说的踪迹了。紧接着对这些书的内容进行了简单介绍。由此可知，第二段主要讲的是科幻小说的开端。
    第三段第一句就提到“Most of the classics of science fiction …"，紧接着又以两个著名的科幻小说家的例子进行说明，可知本段主要讲的是科幻小说中的经典之作。根据线索词“clas-sics of science fiction”也可知C项正确。
    第四段主要讲的是，现代科幻小说家不再写火星人或宇宙冒险，而是写他们对科技发展等的预测或是对未来世界的设想，并且这些作品常带有政治含义。这些都是现代科幻小说的主题。
    第五段的第一句是主题句，主要表明现代科技发展迅速，甚至超越了某些科幻小说，所以作家发现很难赶在科技发展前面。根据线索词“difficult to keep ahead of scientific advances"也可知D项正确。
    由第二段第二句可知，理想社会这个主题不仅在数百年前的著作中出现过，也在现代科幻小说中出现。由此可知，这个主题是一个反复出现的主题。recurrent反复发生的，是“stilloften found”的同义转换。
    根据第三段第二句可知，Jules Verne与H.G.Wells写的科幻小说被翻译成了多国语言。由此可知，Jules Verne写的科幻小说在全世界都有人读。
    由第四段最后一句可知，现代科幻小说有明显的政治含义。implication是undertone的同义转换，有“含义，暗示”的意思。
    由第五段第一句可知，现实中的科技发展超越了某些科幻小说，以至于很多作家感到很难赶在科技发展的前面。

  • 第2题：

    They have given up the hope to save their friend from drowning.

    A:.ended
    B:abandoned
    C:built
    D:strengthen

    答案：B
    解析：
    题千意为“他们放弃了解救他们溺水朋友的希望。” 句中划线词意为“放弃”,B项abandon意为“放弃”。例句：Fearing further attacks, most of the population had abandoned the city．害怕城市进一步受到攻击，大多数人已经离开。A 项意为“结束”。C项意为“建立；加强”。D项意为“加强”。故选B。

  • 第3题：

    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 extent
    of it is still unknown.

    It can be inferred from the passage that the Craighead Caverns presently serve as__________.

    A.an underground testing site
    B.an Indian meeting ground
    C.a tourist attraction
    D.a motor boat race course

    答案：C
    解析：
    【考情点拨】推理判断题。【应试指导】由最后一段可知，Craighead Caverns现在已成为一个旅游胜地。

  • 第4题：

    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-known
    authors, 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.

    答案：D
    解析：
    根据文章第一段的内容可判断A、B、C项均能证明“科幻小说是最受欢迎的书籍之一”。而D项“科幻小说可以追溯到数百年前”，这是在说科幻小说的起源，并不能证明科幻小说很受欢迎。故选D。

  • 第5题：

    The Craighead Caverns have been known________.

    A.through history
    B.since the time of the Indian nations
    C.since 1905
    D.since divers explored them

    答案：B
    解析：

  • 第6题：

    They have learned about（）in recent years.

    • A、several hundreds English words
    • B、hundreds of English words
    • C、hundred of English words
    • D、several hundred English words

    正确答案:B

  • 第7题：

    气体栓塞(air embolism)


    正确答案: 多量空气迅速进入血循环或原已溶解于血液内的气体迅速游离阻塞血管腔的过程称为气体栓塞。

  • 第8题：

    单选题
    They have learned about（）in recent years.
    A

    several hundreds English words

    B

    hundreds of English words

    C

    hundred of English words

    D

    several hundred English words


    正确答案： C
    解析： 暂无解析

  • 第9题：

    多选题
    You are the network consultant from passguide.com. You have been asked for which two features of optical networks allow data to be transmitted over extremely long distances? （）
    A

    Encryption

    B

    Bandwidth limits

    C

    Minimal signal loss

    D

    No EMI


    正确答案： A,C
    解析： 暂无解析

  • 第10题：

    单选题
    The author says “... the public has no reason to panic” (Paragraph 5) because _____.
    A

    the transition is still thousands of years away

    B

    the new transition will come 780000 years from now

    C

    the transition can be precisely predicted by scientists

    D

    the process of the transition will take a very long time to finish


    正确答案： A
    解析：
    见第4题。

  • 第11题：

    单选题
    Some divers always drive carelessly. There is some _____ danger while they are driving.
    A

    painful

    B

    potential

    C

    probable

    D

    primary


    正确答案： B
    解析：
    句意：一些驾驶者开车总是粗心大意。他们开车时存在潜在的危险。potential潜在的，有可能的。painful痛苦的。probable很可能的，大概的。primary主要的，基本的。

  • 第12题：

    单选题
    Intake air flow from a diesel engine turbocharger is directly proportional to engine（）
    A

    exhaust gas pressure

    B

    exhaust gas temperature

    C

    speed

    D

    load


    正确答案： C
    解析： 暂无解析

  • 第13题：

    共用题干
    Science Fiction
    1 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 future
    B:to keep ahead of scientific advances
    C:have political implication
    D:a current theme
    E:read worldwide
    F:a reciirrent theme

    答案：F
    解析：
    第二段第一句提到，人们常认为科幻小说是文学中的新生产物，然而在几百年前所写的书中就能发现科幻小说的踪迹了。紧接着对这些书的内容进行了简单介绍。由此可知，第二段主要讲的是科幻小说的开端。
    第三段第一句就提到“Most of the classics of science fiction …"，紧接着又以两个著名的科幻小说家的例子进行说明，可知本段主要讲的是科幻小说中的经典之作。根据线索词“clas-sics of science fiction”也可知C项正确。
    第四段主要讲的是，现代科幻小说家不再写火星人或宇宙冒险，而是写他们对科技发展等的预测或是对未来世界的设想，并且这些作品常带有政治含义。这些都是现代科幻小说的主题。
    第五段的第一句是主题句，主要表明现代科技发展迅速，甚至超越了某些科幻小说，所以作家发现很难赶在科技发展前面。根据线索词“difficult to keep ahead of scientific advances"也可知D项正确。
    由第二段第二句可知，理想社会这个主题不仅在数百年前的著作中出现过，也在现代科幻小说中出现。由此可知，这个主题是一个反复出现的主题。recurrent反复发生的，是“stilloften found”的同义转换。
    根据第三段第二句可知，Jules Verne与H.G.Wells写的科幻小说被翻译成了多国语言。由此可知，Jules Verne写的科幻小说在全世界都有人读。
    由第四段最后一句可知，现代科幻小说有明显的政治含义。implication是undertone的同义转换，有“含义，暗示”的意思。
    由第五段第一句可知，现实中的科技发展超越了某些科幻小说，以至于很多作家感到很难赶在科技发展的前面。

  • 第14题：

    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 extent
    of 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.

    答案：D
    解析：
    【考情点拨】事实细节题。【应试指导】由第二段最后两句可知答案为D。

  • 第15题：

    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-known
    authors, 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 stories
    B.prediction the results of technical developments on society
    C.predicting the human mind
    D.imagining future worlds which are a reflection of the modern world

    答案：D
    解析：
    文章第二段第二句话“These books were often concerned with the presentation of some form of ideal society，a theme which is still often found in modern stories．”意为“这些书(科幻小说)关注呈现理想社会的一些形态，这个主题在现代的小说中也可以找到”。由这句话推断，过去的科幻小说应该注重于呈现他们根据现实社会所想象的理想的社会，故选D。

  • 第16题：

    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-known
    authors, 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 Fiction
    B.The Popularity of Science Fiction
    C.The Origin of Science Fiction
    D.The Themes of Science Fiction

    答案：A
    解析：
    选项A最具有概括性，能概括全文所讲的内容。

  • 第17题：

    How long have you lived in London? （）

    AI moved here from Paris.

    BMy whole life.

    CI‘ve worked here for almost 10 years.

    DI‘ve never traveled there.


    C
    略

  • 第18题：

    You are the network consultant from passguide.com. You have been asked for which two features of optical networks allow data to be transmitted over extremely long distances? （）

    • A、Encryption
    • B、Bandwidth limits
    • C、Minimal signal loss
    • D、No EMI

    正确答案:C,D

  • 第19题：

    单选题
    Starting air for auxiliary engines may be taken directly from the main reservoirs or through （）.
    A

    an auxiliary reservoir

    B

    a controlling air bottle

    C

    an emergency air compressor

    D

    a main air compressor


    正确答案： B
    解析： 暂无解析

  • 第20题：

    名词解释题
    气体栓塞(air embolism)

    正确答案： 多量空气迅速进入血循环或原已溶解于血液内的气体迅速游离阻塞血管腔的过程称为气体栓塞。
    解析： 暂无解析

  • 第21题：

    单选题
    We may infer from the fourth paragraph that ______.
    A

    humans have been growing food crops more than ten thousand years.

    B

    humans have learned how to produce biofuels for a long time.

    C

    humans are just on the beginning of making biofuels.

    D

    a cell wall includes four hemicellulose.


    正确答案： C
    解析：
    推断判断题。由题干定位至第四段。由首句Humans have been growing food crops for 10,000 years可知，A中more than与原文不符，故排除；由but the effort to produce fuel down on the farm is in its fancy可见B错；由段中 We’re at such a basic stage，可知，从作物提取燃料还处于初级阶段，C正确；由本段倒数第二句可知cell walls是由four hemicelluloses, along with cellulose and lignin构成，并且由a cell wall engineered to include more hemicellulose可知一个细胞壁不仅仅只有four hemicellulose(半纤维素), 排除D。

  • 第22题：

    单选题
    Upon underwater（）by divers，there are no apparent（）on the bottom plates of the said vessel.
    A

    detection，defects

    B

    defection，defects

    C

    defects，defection

    D

    defects，detection


    正确答案： D
    解析： 暂无解析

  • 第23题：

    单选题
    How long have you lived in London? （）
    A

    I moved here from Paris.

    B

    My whole life.

    C

    I‘ve worked here for almost 10 years.

    D

    I‘ve never traveled there.


    正确答案： A
    解析： 暂无解析

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