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How does the U.S. rank in the international human-capital standings? That’s a tricky question. Over time the American economy has shown more dynamism and sustained growth than just about any other. But if you look only at the performance of the average American high school student on international tests, you would think it was a nation of dim-witted dullards. What explains this paradox? To some extent, the answer must be the quality of American universities, which are highly efficient, intensely competitive and wonderfully endowed—and which increasingly recruit the bust students from around the world. But university professors aren’t magicians; however skilled they may be, if their inputs from high schools are garbage, their outputs of graduates will not be much better.

While it is true that living organisms are profoundly affected by their environment, it is equally important to remember that many organisms are also capable of altering their habitat significantly, sometimes limiting their own growth. The influence of the biological component of an ecosystem is often greater in fresh waters than in marine or terrestrial systems, because of the small size of many freshwater bodies. Many of the important effects of organisms are related to their physiology, especially growth and respiration. By their growth many species can deplete essential nutrients within the system, thus limiting their own growth or that of other species.

Intelligence at best is an assumptive construct ---the meaning of the word has never been clear. There is more agreement on the kinds of behavior referred to by the term than there is on how to interpret or classify them. But it is generally agreed that a person of high intelligence is one who can grasp ideas readily, make distinctions, reason logically, and make use of verbal and mathematical symbols in solving problems. An intelligence test is a rough measure of a child’s capacity for learning, particularly for learning the kinds of things required in school. It does not measure character, social adjustment, physical endurance, manual skills, or artistic abilities. It is not supposed to ---it was not designed for such purposes. To criticize it for such failure is roughly comparable to criticizing a thermometer for not measuring wind velocity.

The method of scientific investigation is nothing but the expression of the necessary mode of working of the human mind; it is simply the mode by which all phenomena are reasoned about and given precise and exact explanation. There is no more difference, but there is just the same kind of difference, between the mental operations of a man of science and those of an ordinary person., as there is between the operations and methods of a baker or of a butcher weighing out his goods in common scales, and the operations of a chemist in performing a difficult and complex analysis by means of his balance and finely graded weights. It is not that the scales in the one case, and the balance in other, differ in the principles of their construction or manner of working; but that the latter is a much finer apparatus and of course much more accurate in its measurement than the former.

The earliest controversies about the relationship between photography and art centered on whether photography’s fidelity to appearances and dependence on a machine allowed it to be a fine art as distinct from merely a practical art. Throughout the nineteenth century, the defense of photography was identical with the struggle to establish it as a fine art. Against the charge that photography was a soulless, mechanical copying of reality; photographers asserted that it was instead a privileged way of seeing, a revolt against commonplace vision, and no less worthy an art than painting.Ironically, now that photography is securely established as a fine art, many photographers find it pretentious or irrelevant to label it as such. Serious photographers variously claim to be finding, recording, impartially observing, witnessing events, exploring themselves —anything but making works of art. In the nineteenth century, photography’s association with the real world placed it in an ambivalent relation to art: late in the twentieth century an ambivalent relation exists because of the modernist heritage in art. That important photographers are no longer willing to debate whether photography is or is not a fine art, except to proclaim that their own work is not involved with art, shows the extent to which they simply take for granted the concept of art imposed by the triumph of Modernism: the better the art, the more subversive it is of the traditional aims of art.Photographers’ disclaimers of any interest in making art tell us more about the harried status of the contemporary notion of art than about whether photography is or is not art. For example, those photographers who suppose that, by taking pictures, they are getting away from the pretensions of art as exemplified by painting remind us of those Abstract Expressionist painters who imagined they were getting away from the intellectual austerity of classical Modernist painting by concentration on the physical act of painting. Much of photography’s prestige today derives from the convergence of its aims with those of recent art, particularly with the dismissal of abstract art implicit in the phenomenon of Pop during the 1960’s. Appreciating photographs is a relief to sensibilities tired of the mental exertions demanded by abstract art. Classical modernist painting --- that is abstract art as developed in different ways by Picasso, Candinsky and Matisse ---presupposes highly developed skills of looking and a familiarity with other paintings and the history of art, photography, like Pop painting, and reassures viewers that art is not hard: photography seems to be more about its subjects than about art.Photography, however, has developed all the anxieties and self-consciousness of a classic Modernist art. Many professionals privately have begun to worry that the promotion of photograph as an activity subversive of the traditional pretensions of art has gone so far that the public will forget that photograph is a distinctive and exalted activity ---in short, an art.1.In the passage, the author is primarily concerned with（） .2.Which of the following adjectives best describes ‘the concept of art imposed by the triumph of Modernism” as the author represents it in the second paragraph？ (The sentence in italics.)3.The author introduces Abstract Expressionist painters (in the third paragraph) in order to（）.4.According to the author, the nineteenth——century defenders of photography mentioned in the passage stressed that photography was（）.5.According to the passage, which of the following best explains the reaction of serious contemporary photographers to the question of whether photography is an art?6.According to the passage, certain serious contemporary photographers expressly make which of the following claims about their photographs?7.It can be inferred from the passage that the author most probably considers serious contemporary photography to be a（）

Two relatively recent independent development stand behind the current major researcheffort on nitrogen fixation,(固氮)the process by which bacteria symbiotically render leguminous (豆科的)plants independent of nitrogen fertilizer , one development has been the rapid , sustained increase in the price of nitrogen fertilizer. The other development has been the rapid growth of knowledge of and technical sophistication in genetic engineering. Fertilizer prices, largely tied to the price of natural gas，huge amounts of which go into the manufacture of fertilizer , will continue to represent an enormous and escalating , economic burden on modem agriculture , spurring the search for alternatives to synthetic (合成的) fertilizers . And genetic engineering is just the sort of fundamental breakthrough that opens up prospects of wholly novel alternatives. One such novel idea is that of inserting into the chromosomes (染色体)of plants discrete genes that are not a part of the plants’ natural constitution: specifically, the idea of inserting into nonleguminous plants the genes , if they can be identified and isolated, that fit the leguminous plants to be hosts for nitrogen-fixing bacteria.Nitrogen fixation is a process in which certain bacteria use atmospheric nitrogen gas , which green plant cannot directly utilize, to produce ammonia (氨)a nitrogen compound plants can use . It is one of nature’s great ironies that the availability of nitrogen in the soil frequently sets an upper limit on plant growth even though the plants’s leaves are bathed in a sea of nitrogen gas. The leguminous plants --- among them crop plants such as soybeans, peas, alfalfa, and clover-have solved the nitrogen supply problem by entering into a symbiotic(共生的)relationship with the bacterial genus Rhizobium (根瘤菌); as a matter of fact, there is a specific strain of Rhizobium for each species of legume . The host plant supplies the bacteria with food and a protected habitat and receives surplus ammonia in exchange. Hence, legumes can thrive in nitrogen --- depleted soil.Unfortunately most of the major food crops including maize, wheat, rice, and potatoes cannot. On the contrary, many of the high-yielding hybrid (杂种的)varieties of these food crops bred during the Green Revolution of the 1960’s were selected specifically to give high yields in response to generous applications of nitrogen fertilizer. This poses an additional formidable challenge to plant geneticists: they must work on enhancing fixation within the existing symbioses. Unless they succeed, the yield gains of the Green Revolution will be largely lost even if the genes in legumes that equip those plants to enter into a symbiosis with nitrogen fixers are identified and isolated, and even if the transfer of those gene complexes, once they are found, becomes possible. The overall task looks forbidding, but the stakes are too high not to undertake it.1.The primary purpose of the passage is to（） .2.According to the passage, there is currently no strain of Rhizobium that can enter into a symbiosis with（） .3.The passage implies which of the following is true of the bacterial genus Rhizobium?4.It can be inferred from the passage that which of the following was the most influential factor in bringing about intensified research on nitrogen fixation?5.Which of the following situations is most closely analogous to the situation described by the author as one of nature’s great ironies.( the sentence in italics in paragraph 2)6.According to the passage, the ultimate goal of the current research on nitrogen fixation is to develop （）.7.The author regards the research program under discussion as（） .8.Most nearly parallel, in its fundamental approach, to the research program described in the passage would be a program designed to（）

Why should anyone buy the latest volume in the ever-expanding Dictionary of NationalBiography? I do not mean that it is bad, as the reviewers will agree. But it will cost you 65 pounds. And have you got the rest of volumes? You need the basic 22 plus the largely decennial supplements to bring the total to 31. Of course, it will be answered, public and academic libraries will want the new volume. After all, it adds 1068 lives of people who escaped the net of the original compilers. Yet in 10 years’ time a revised version of the whole caboodle, called the New Dictionary of National Biography, will be published. Its editor. Professor Colin Matthew, tells me that he will have room for about 50,0001ives，some 13,000 more than in the current DNB. This rather puts the 1,068 in Missing Persons in the shade.When Dr. Nicholls wrote to The Spectator in 1989 asking for names of people whom readers had looked up in the DNB and been disappointed not to find, she says that she received some 1009000suggestions .( Well, she had written to “ other quality newspapers” too .) As soon as her committee had whittled the numbers down, the professional problems of an editor began. Contributors didn’t file copy on time; some who did sent too much. 50,000 words instead of 500 is a record, according to Dr. Nicholls. There remains the dinner-party game of who’s out. That is a game that the reviewers have played and will continue to play. Criminals were may initial worry. After all, the original edition of the DNB boasted. Malefactors whose crimes excite a permanent interest have received hardly less attention than benefactors. Mr. John Gross clearly had similar anxieties, for he complains that, while the murderer Christie is in. Crippen is out. One might say in reply that the injustice of the hanging of Evans instead of Christies (entry in Missing Persons) notes. But then Crippen was reputed as the first murderer to be caught by telegraphy (he had tried to escape by ship to America).It is surprising to find Max Miller excluded when really not very memorable names get in. There has been a conscious effort to put in artists and architects from the Middle Ages. About their lives not much is always known.Of Hugo of Bury St Edmunds, a 12th -century illuminator whose dates of birth and death are not recorded his biographer comments. “Whether or not Huge was a wall-painter, the records of his activities as carver and manuscript painter attest to his versatility”. Then there had to be more women, too (12 per cent, against the original DBN’s 3), such as Roy Strong’s subject, the Tudor painter Levina Teerlinc, of whom he remarks, “Her most characteristic feature is a head attached to a too small, spindly body. Her technique remained awkward, thin and often cursory.” Doesn’t seem to qualify her as a memorable artist. Yet it may be better than the record of the original DNB, which included lives of people who never existed (such as Merlin) and even managed to give thanks to J.W. Clerke as a contributor. Though, as a later edition admits in a shamefaced footnote, “except for the entry in the List of contributors there is no trace of J.W. Clerke”.1.The writer suggests that there is no sense in buying the latest volume（）.2.On the issue of who should be included in the DNB, the writer seems to suggest that （）.3.Crippen was absent from the DNB （）.4.The author quoted a few entries in the last paragraph to（）.5.Throughout the passage, the writer’s tone towards the DNB was（）.

In general, our society is becoming one of giant enterprises directed by a bureaucratic management in which man becomes a small well-oiled cog in the machinery. The oiling is done with higher wages, well-ventilated factories and piped music, and by psychologists and “human-relations” experts. Yet all this oiling does not alter the fact that man has become powerless that he does not wholeheartedly participate in his work and that he is bored with it. In fact, the blue and the white-collar workers have become economic puppets who dance to the tune of automated machines and bureaucratic management.The worker and employee are anxious, not only because they might find themselves out of a job. They are anxious also because they are unable to acquire any real satisfaction or interest in life. They live and die without ever having confronted the fundamental realities of human existence as emotionally and intellectually independent and productive human beings.Those higher up on the social ladder are no less anxious. Their lives are no less empty than those of their subordinates. They are even more insecure in some respects. They are in a highly competitive race. To be promoted or to fall behind is not a matter of salary but even more a matter of self-respect. When they apply for their first job, they are tested for intelligence as well as for the tight mixture of submissiveness and independence. From that moment on they are tested again and again-by the psychologists, for whom testing is a big business, and by their superiors, who judge their behavior, sociability, capacity to get along, etc. This constant need to prove that one is as good as or better than one’s fellow-competitor creates constant anxiety and stress, the very causes of unhappiness and illness.Am I suggesting that we should return to the preindustrial mode of production or to nineteenth-century “free enterprise” capitalism? Certainly not. Problems are never solved by returning to a stage which one has already outgrown. I suggest transforming our social system from a bureaucratically managed industrialism in which maximal production and consumption are ends in themselves into a humanist industrialism in which man and full development of his potentialities-those of love and of reason-are the aims of all social arrangements. Production and consumption should serve only as means to this end, and should be prevented from ruling man.1.By “a well-oiled cog in the machinery” the author intends to render the idea that man is（）.2.The real cause of the anxiety of the workers and employees is that （）3.From the passage we can infer that real happiness of life belongs to those （）.4.To solve the present social problems the author suggests that we should（）.5.The author’s attitude towards industrialism might best be summarized as one of （）.

Children’s literature traces its beginnings to preliterate times, when ancient storytellers passage tales and legends from generation to generation in the oral tradition. William Caxton, who established England’s first printing press, published books of etiquette, fables and legends. However, these didn’t constitute a body of work that could be considered literature for children. Because children at that time were considered “miniature adults”, books were didactic in nature. The content for young readers consisted mainly of religious instruction, rules of behavior, ethical messages, and moral platitudes. In 1744 Englishman John Newberry changed children’s publishing when he began to create books with attractive formats, quality illustrations, and sturdy bindings, which were designed primarily for children to enjoy. The oldest, and most prestigious award given for children’s books published in America, is the Newberry Medal.In the following century, children’s literature began to bloom. Hans Christian Andersen wrote wonderful stories like “ The Ugly Duckling”, and “ The Little Mermaid”, and Grimm brothers collected two volumes of German folktales that included stories such as “ Snow White” and “ Rumpelstiltskin Childhood came to be recognized as a joyful and carefree period of life, and books celebrating it began to be published, Charles Dodgson ( Lewis Carrol) wrote the fantast “ Alice in Wonderland”, the first book that was intended purely for children’s enjoyment without any pretense of instruction. Edwards Lear’s books of nonsense poetry delighted both young and old readers. In North America, books for a young audience were becoming popular as well. Kate Douglas Wiggin wrote “Rebecca of Sunny brook Fram”, Louisa May Alcott wrote “Little Women’’, and Samuel Clemens (Mark Twain) created Tom Sawyer and Huckleberry Finn. By the end of the century, the pious and moralistic books of earlier times had been replaced by writing designed to amuse and entertain a young audience. In the 1800s color printing was introduced, and by the middle of the 19th century, the rough illustrations that characterized earlier children’s books had been replaced by works of art that captured the word and some of the story.1.According to the passage, the early books of etiquette, fables, and legends could not really be considered children’s literature because（）.2.According to the passage, what changed children’s publishing in 1744?3.The word “sturdy” in line 11 is closest in meaning to（）.4.What does the author mean by the statement “children’s literature began to bloom” in line 15?5.According to the passage “Alice in Wonderland” was an example of （）.6.The word “characterized” in line 32 is closest in meaning to（） .7.What impact did color printing have on children’s books?

The industrialization of Europe which started in the 18th century produced urban slims which were swept periodically by epidemics of typhoid and typhus. While isolated geographically from the scourges of Europe, America was occasionally hit with epidemics of its own, especially in the growing east coast cities. Recognizing that disease may be coming from the ships that docked in their ports, cities instituted quarantines during outbreaks. Treatments for widespread disease, however, did not improve.In 1847, the newly-formed American Medical Association sponsored an investigation of large U.S cities and found that living conditions for many residents had become as bad as the worst slums of Europe. It concluded that without improvements in hygiene and living standards, European-type epidemics would soon hit American cities. It also advocated collecting vital statistics to track the country’s birth and death rates. Soon after this, many bureaus of vital statistics were organized. Including in Ohio, where birth and death statistics were collected at the country level beginning in 1867. Local sanitary commissions formed in cities and towns, spurred on by reform movements which stressed healthier living and clean water. The Massachusetts Sanitary Commission, for example, sought better venting of city homes to remove any noxious odors and fumes that might cause disease. To provide plentiful water, 32 waterworks were built in the country by 1825, and almost 600 were added by 1880. Unfortunately it was assumed that free-flowing water was pure, so the first filtration plant was not built until 1871. The first national convention to establish uniform quarantine laws, met in Philadelphia in May 1857, and four more such conventions to discuss public health issues were held before the Civil War disrupted the movement.The American Public Health Association was founded in 1872 by some of those who attended these earlier conventions. The following year the number of boards of health in the U.S. Increased from 4 to 123. The most significant event in the public health movement, however, was the development of the germ theory and the realization that disease could be contagious.1.America was protected from the periodic epidemics of typhoid and typhus in Europe because of （）.2.The word “hygiene” in line 13 is closest in meaning to（） .3.What fear did the American Medical Association have?4.Which of the following actions does the author imply was done in response to the American Medical Association recommendations?5.The word “noxious” in line 22 is closest in meaning to .6.The first filtration plant was not built until 1871 because（） .7.The word “contagious” in line 36 is closest in meaning to（） .8.Throughout the passage, the author implies that public health （）.

科学的最终目的是提供一种描绘整个宇宙的简单理论。然而，大多科学家实际采用的方法是将这个问题分成两个部分。第一部分是一些告知我们宇宙随着时间的推移而变化的方式的规律。第二部分是对宇宙初始状态的疑问。有些人认为科学只应该关注第一部分。他们把宇宙初始状态的问题看成是玄学或宗教要回答的问题。

计算机病毒系一小撮存心不良的黑客所为，这些人纯属为了搞恶作剧而编造有毒软件。病毒是短行的软件代码，具有以下三个特征：第一，病毒把自己隐藏在合法的文件或程序之中；第二，病毒像细菌那样进行复制以在计算机之间传播；第三，病毒对计算机的所作所为可令你气得发疯。

To our view, the future belongs to those who will know how to perceive the mysterious borderline which separates the ugly from the beautiful. This philosophy has dominated most of the great civilizations of the past and is fundamentally our own western way of looking at the world.I am confident that with a better understanding of each other, there will be also a corresponding modification of our attitudes toward the achievements of the Japanese people.It is only through stronger ties among all of us, through the realization of a truly triangular world of cooperative effort in which the United States, Europe, and Japan will be able to reinforce their respective ties, that one will be capable of planning the general scenario of the 21st century, and this within a broader picture of international cooperation among all civilized people of this planet.

In order to meet the global challenges in today’s highly competitive environment, a firm’s strategic cost management programs should not restrict their attention to the cost structure of the firm or the firm’s cost performance relative to that of other firms and, in particular, competitors.There are two benefits that can be derived from such extra-organizational cost analysis. The first benefit is a steady stream of ideas that can be used to make a firm more efficient and its products more competitive. These benefits are derived from all aspects of extra-organizational cost analysis, but especially from product teardown and participation in roundtables. The second benefit is a comparison of a firm’s own progress at becoming efficient with the progress of other firms.

The Internet, once the domain of education and government, has suddenly exploded into the commercial sector. From this we will witness dramatic changes in the way we work and the systems we will use. Java will have a very important role to play in this digital revolution allowing executable content that are safe to traverse and ride the Internet onto our desktops. A rich, interactive, three-dimensional “Second Web” is expected to evolve which will help to attract a larger audience than today’s two-dimensional text-pictures model.New technologies are already beginning to transform the World Wide Web from its page-centric system to one more like the real world-interactive, three-dimensional and animate.“The First Web” is primarily a medium for document access. It is fundamentally a reading experience with benefits often expressed in the savings achieved by eliminating paper-based processes. As a result, the Web applies to a limited part of our lives. It has not become a mass medium for the home like telephones and television sets.

The distinction between the mechanization of the past and what is happening now is, however, not a sharp one. At one extreme we have the electronic computer with its quite remarkable capacity for discrimination and control, while at the other end of the scale are “transfer machines”, as they are now called, which may be as simple as a conveyor belt to another. An automatic mechanism is one which has a capacity for self-regulation; that is, it can regulate or control the system or process without the need for constant human attention or adjustment. Now people often talk about “feedback” as being an essential factor of the new industrial techniques, upon which is based an automatic self-regulating system and by virtue of which any deviation in the system from desired conditions can be detected, measured, reported and corrected. When “feedback” is applied to the process by which a large digital computer runs at the immense speed through a long series of sums, constantly rejecting the answers until it finds one to fit a complex set of facts which have been put to it, it is perhaps different in degree from what we have previously been accustomed to machines.

For centuries, explorers have risked their lives venturing into the unknown for reasons that were to varying degrees economic and nationalistic. Columbus went west to look for better trade routes to the Orient and to promote the greater glory of Spain. Lewis and Clark journeyed into the American wilderness to find out what the U.S had acquired when it purchased Louisiana, and the Appolo astronauts rocketed to the moon in a dramatic show of technological muscle during the cold war.Although their missions blended commercial and political-military imperatives, the explorers involved all accomplished some significant science simply by going where no scientists had gone before.Today Mars looms as humanity’s next great terra incognita. And with doubtful prospects for a short-term financial return, with the cold war a rapidly fading memory and amid a growing emphasis on international cooperation in large space ventures, it is clear that imperatives other than profits or nationalism will have to compel human beings to leave their tracks on the planet’s reddish surface. Could it be that science, which has long played a minor role in exploration, is at last destined to take leading role? The question naturally invites a couple of others: Are there experiments that only humans could do on Mars? Could those experiments provide insights profound enough to justify the expense of sending people across interplanetary space?With Mars the scientific stakes are arguably higher than they have ever been. The issue of whether life existed on the planet, and whether it persists to this day, has been highlighted by mounting evidence that the Red Planet once had abundant stable, liquid water and by the continuing controversy over suggestions that bacterial fossils rode to Earth on a meteorite from Mars. A more conclusive answer about life on Mars, past or present, would give researchers invaluable data about the range of conditions under which a planet can generate the complex chemistry that leads to life. If it could be established that life arose independently on Mars and Earth, the finding would provide the first concrete clues in one of the deepest mysteries in all of science: the prevalence of life in the universe.1.According to the passage, the chief purpose of explorers in going to unknown place in thepast was（）.2.At present, a probable inducement for countries to initiate large-scale space ventures is （）.3.What is the main goal of sending human missions to Mars?4.By saying “With Mars the scientific stakes are arguably higher than they have ever been”(linel, Para.4), the author means that （）.5.The passage tells us that proof of life on Mars would（）.

Coral reefs are one of the most fragile, biologically complex, and diverse marine ecosystem on Earth. This ecosystem is one of the fascinating paradoxes of the biosphere: how do clear and thus nutrient-poor waters support such prolific and productive communities? Part of the answer lies within the tissues of the corals themselves. Symbiotic cells of algae known as zoozanthellae carry out photosynthesis using the metabolic wastes of the coral thereby producing food for themselves, for their corals, hosts, and even for other members of the reef community. This symbiotic process allows organisms in the reef community to use sparse nutrient resource efficiently.Unfortunately for coral reefs, however, a variety of human activities are causing worldwide degradation of shallow marine habitats by adding nutrients to the water. Agriculture, slash---and ---bum land clearing, sewage disposal and manufacturing that creates waste by-products all increase nutrient loads in these waters. Typical symptoms of reef decline are destabilized herbivore populations and an increasing abundance of algae and filter-feeding animals. Declines in reef communities are consistent with observations that nutrient input is increasing in direct proportion to growing human populations, thereby threatening reef communities sensitive to subtle changes in nutrient input to their waters.1.The passage is primarily concerned with（） .2.The passage suggests which of the following about coral reef communities?3.The author refers to “filter-feeding animals” (line 17) in order to （）.4.According to the passage, which of the following is a factor that is threatening the survival of coral reef communities?5.It can be inferred from the passage that the author describes coral reef communities as paradoxical most likely for which of the following reasons?

Australian researchers have discovered electroreceptors (sensory organs designed to respond to electrical fields) clustered at the tip of the spiny anteater’s snout. The researchers made this discovery by exposing small areas of the snout to extremely weak electrical fields and recording the transmission of resulting nervous activity to the brain. While it is true that tactile receptors, another kind of sensory organ on the anteater’s snout, can also respond to electrical stimuli, such receptors do so only in response to electrical field strengths about 1,000 times greater than those known to excite electroreceptors.Having discovered the electroreceptor, researchers are now investigating how anteaters utilize such a sophisticated sensory system. In one behavioral experiment, researchers successfully trained an anteater to distinguish between two troughs of water, one with a weak electrical field and the other with none. Such evidence is consistent with researcher’s hypothesis that anteaters use electroreceptor to detect electrical signals given off by prey; however, researchers as yet have been unable to detect electrical signals emanating from termite mounds, where the favorite food of anteaters live. Still, researchers have observed anteaters breaking into a nest of ants at an oblique angle and quickly locating nesting chambers. This ability quickly to locate unseen prey suggests, according to the researchers, that the anteaters were using their electroreceptor to locate the nesting chambers.1.According to the passage, which of the following is a characteristic that distinguishes electroreceptors from tactile receptors?2.Which of the following can be inferred about the experiment described in the first paragraph?3.The author of the passage most probably discusses the function of tatile receptors (lines6—9) in order to（） .4.Which of the following can be inferred about anteaters from the behavioral experiment mentioned in the second paragraph?5. The passage suggests that the researchers mentioned in the second paragraph who observed anteaters break into a nest of ants would most likely agree with which of the following statements?6.Which of the following, if true, would most strengthen the hypothesis mentioned in lines 15—16?

Studies of the Weddell seal in the laboratory have described the physiological mechanisms that allow the seal to cope with the extreme oxygen deprivation that occurs during its longest dives, which can extend 500 meters below the ocean’s surface and last for over 70 minutes. Recent field studies, however, suggest that during more typical dives in the wild, this seal’s physiological behavior is different.In the laboratory, when the seal dives below the surface of the water and stops breathing, its heart beats more slowly, requiring less oxygen and its arteries become constricted, ensuring that the seal’s blood remains concentrated near those organs most crucial to its ability to navigate underwater. The seal essentially shuts off the flow of blood to other organs, which either stop functioning until the seal surfaces or switch to an anaerobic (oxygen-independent) metabolism. The latter results in the production of large amounts of lactic acid which can adversely affect the PH of the seal’s blood but since the anaerobic metabolism occurs only in those tissues which have been isolated from the seal’s blood supply, the lactic acid is released into the seal’s blood only after the seal surfaces, when the lungs, liver, and other organs quickly clear the acid from the seal’s blood stream.Recent field studies, however, reveal that on dives in the wild, the seal usually heads directly for its prey and returns to the surface in less than twenty minutes. The absence of high levels of lactic acid in the seal’s blood after such dives suggests that during then, the seal’s organs do not resort to the anaerobic metabolism observed in the laboratory, but are supplied with oxygen from the blood. The seal’s longer excursions underwater, during which it appears to be either exploring distant routes or evading a predator, do evoke the diving response seen in the laboratory. But why do the seal’s laboratory dives always evoke this response, regardless of their length or depth? Some biologists speculate that because in laboratory dives the seal is forcibly submerged, it does not know how long it will remain underwater and so prepares for the worst.1.The passage provides information to support which of the following generalizations?2.It can be inferred from the passage that by describing the Weddell seal as preparing “for the worst” lines 31 —32, biologists mean that it （）.3.The passage suggests that during laboratory dives. The PH of the Weddell seal’s blood is（）4.Which of the following best summarizes the main point of the passage?not adversely affected by production of lactic acid because .5.According to the author, which of the following is true of the laboratory studies mentioned in line 1?6.The author cites which of the following as characteristic of the Weddell seal’s physiological behavior during dives observed in the laboratory?I. A decrease in the rate at which the seal’s heart beats.II. A constriction of the seal’s arteries.III. A decrease in the levels of lactic acid in the seal’s blood.IV. A temporary halt in the functioning of certain organs.7.The passage suggests that because Weddell seals are forcibly submerged during laboratory dives, they do which of the following?

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