GMAT逻辑复习资料-逻辑大全分类-Explaination

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大全-16-5.        Archaeologists have found wheeled ceramic toys made by the Toltec, twelfth-century inhabitants of what is now Veracruz. Although there is no archaeological evidence that the Toltec used wheels for anything but toys, some anthropologists hypothesize that wheeled utility vehicles were used to carry materials needed for the monumental structures the Toltec produced.
Which of the following, if true, would most help the anthropologists explain the lack of evidence noted above?
wheeled：有某数量轮子的,   ceramic：陶器的
(A) The Toltec sometimes incorporated into their toys representations of utensils or other devices that served some practical purpose.
(B) Any wheeled utility vehicles used by the Toltec could have been made entirely of wood, and unlike ceramic, wood decays rapidly in the humid climate of Veracruz.
制造wheeled utility vehicles的材质是木头，很容易腐烂，不像陶器那样容易保存。
(C) Carvings in monument walls suggest that the Toltec’s wheeled ceramic toys sometimes had ritual uses in addition to being used by both children and adults as decorations and playthings.
(D) Wheeled utility vehicles were used during the twelfth century in many areas of the world, but during this time wheeled toys were not very common in areas outside Veracruz.
(E) Some of the wheeled ceramic toys were found near the remains of monumental structures.

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大全-10-16.        In the 1970’s there was an oversupply of college graduates. The oversupply caused the average annual income of college graduates to fall to a level only 18 percent greater than that of workers with only high school diplomas. By the late 1980’s the average annual income of college graduates was 43 percent higher than that of workers with only high school diplomas, even though between the 1970’s and the late 1980’s the supply of college graduates did not decrease.
Which of the following, if true, in the late 1980’s, best reconciles the apparent discrepancy described above?
(A) The economy slowed, thus creating a decreased demand for college graduates.
(B) The quality of high school education improved.
(C) Compared to the 1970’s, a greater number of high schools offered vocational guidance programs for their students.
(D) The proportion of the population with at least a college-level education increased.
(E) There was for the first time in 20 years an oversupply of job seekers with only high school diplomas.

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大全-10-8.        For the safety-conscious Swedish market, a United States manufacturer of desktop computers developed a special display screen that produces a much weaker electromagnetic field surrounding the user than do ordinary screens. Despite an advantage in this respect over its competitors, the manufacturer is introducing the screen into the United States market without advertising it as a safety improvement.
Which of the following, if true, provides a rationale for the manufacturer’s approach to advertising the screen in the United States?
(A) Many more desktop computers are sold each year in the United States market than are sold in the Swedish market.
(B) The manufacturer does not want its competitors to become aware of the means by which the company has achieved this advance in technology.
(C) Most business and scientific purchasers of desktop computers expect to replace such equipment eventually as better technology becomes available on the market.
(D) An emphasis on the comparative safety of the new screen would call into question the safety of the many screens the manufacturer has already sold in the United States.
(E) Concern has been expressed in the United States over the health effects of the large electromagnetic fields surrounding electric power lines.

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大全-10-4.        The fossil record shows that the climate of North America warmed and dried at the end of the Pleistocene period. Most of the species of large mammals then living on the continent became extinct, but the smaller mammalian species survived.
Which of the following, if true, provides the best basis for an explanation of the contrast described above between species of large mammals and species of small mammals?
(A) Individual large mammals can, in general, travel further than small mammals and so are more able to migrate in search of a hospitable environment.
(B) The same pattern of comparative success in smaller, as opposed to larger, species that is observed in mammals is also found in bird species of the same period.
(C) The fossil record from the end of Pleistocene period is as clear for small mammals as it is for large mammals.
(D) Larger mammals have greater food and space requirements than smaller mammals and are thus less able to withstand environmental change.
(E) Many more of the species of larger mammals than of the species of smaller mammals living in North America in that period had originated in climates that were warmer than was that of North America before the end of the Pleistocene period.

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大全-10-1.        In 1985 in the country of Alissia, farmers brought to market a broccoli crop that was one-and-a-half times as large as the 1985 broccoli crop in its neighbor country, Barbera. Yet total quantities of broccoli available for sale to consumers in Alissia were smaller than were total quantities in Barbera in 1985.
Which of the following, if true, in 1985, contributes most to an explanation of why there was less broccoli available for sale to consumers in Alissia than in Barbera?
(A) Barbera’s farmers produced much more cabbage than did Alissia’s farmers.
(B) Barbera’s farmers produced fewer heads of broccoli per acre than did Alissia’s farmers.
(C) Alissia exported a much higher proportion of its broccoli crop than did Barbera.
(D) Broccoli was much more popular among consumers in Alissia than in Barbera.
(E) Alissia had more land suitable for growing broccoli than did Barbera.

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大全-11-17.        Since 1975 there has been in the United States a dramatic decline in the incidence of traditional childhood diseases such as measles. This decline has been accompanied by an increased incidence of Peterson’s disease, a hitherto rare viral infection, among children. Few adults, however, have been affected by the disease.
Which of the following, if true, would best help to explain the increased incidence of Peterson’s disease among children?
(A) Hereditary factors determine in part the degree to which a person is susceptible to the virus that causes Peterson’s disease.
(B) The decrease in traditional childhood diseases and the accompanying increase in Peterson’s disease have not been found in any other country.
(C) Children who contract measles develop an immunity to the virus that causes Peterson’s disease.
(D) Persons who did not contract measles in childhood might contract measles in adulthood, in which case the consequences of the disease would generally be more severe.
(E) Those who have contracted Peterson’s disease are at increased risk of contracting chicken pox.

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大全-12-5.        The number of musicians employed to play accompaniment for radio and television commercials has sharply decreased over the past ten years. This has occurred even though the number of commercials produced each year has not significantly changed for the last ten years.
Which of the following, if it occurred during the past ten years, would contribute LEAST to an explanation of the facts above?
(A) The type of music most popular for use in commercials has changed from a type that requires a large number of instruments to a type that requires very few instruments.
(B) There has been an increase in the number of commercials that use only the spoken word and sound effects, rather than musical accompaniment.
(C) There has been an increase in the number of commercials that use a synthesizer, an instrument on which one musician can reproduce the sound of many musicians playing together.
(D) There has been an increase in the number of commercials that use prerecorded music as their only source of music.
(E) There has been an increase in the number of commercials that use musicians just starting in the music industry rather than musicians experienced in accompanying commercials.

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大全-12-3.        Which of the following, if true, best reconciles the discrepancy between the increase in unemployment and the increase in jobs in the manufacturing industry of Alameda?
(A) Many products that contain microelectronic components are now assembled completely by machine.
(B) Workers involved in the various aspects of the manufacturing processes that use microelectronic technology need extensive training.
(C) It is difficult to evaluate numerically what impact on job security the introduction of microelectronics in the workplace had before 1979.
(D) In 1990 over 90 percent of the jobs in Alameda’s manufacturing companies were filled by workers who moved to Alameda because they had skills for which there was no demand in Alameda prior to the introduction of microelectronics there.
(E) Many workers who have retired from the manufacturing industry in Alameda since 1979 have not been replaced by younger workers.

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Questions 3-4 are based on the following.
The proportion of manufacturing companies in Alameda that use microelectronics in their manufacturing processes increased from 6 percent in 1979 to 66 percent in 1990. Many labor leaders say that the introduction of microelectronics is the principal cause of the great increase in unemployment during that period in Alameda. In actual fact, however, most of the job losses were due to organizational changes. Moreover, according to new figures released by the labor department, there were many more people employed in Alameda in the manufacturing industry in 1990 than in 1979.
用ME系统的公司所占比例从1979年的6%上升到1990年的66%，劳工领袖说ME系统的引进是大规模失业的主要原因。然而事实上，大部分工作丢失都是因为结构变化，再者，根据劳工部统计，1990年受佣的人数比1979年要多。为何被雇佣人数增加的同时失业率还增加了。

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大全-13-11.        An experiment was done in which human subjects recognize a pattern within a matrix of abstract designs and then select another design that completes that pattern. The results of the experiment were surprising. The lowest expenditure of energy in neurons in the brain was found in those subjects who performed most successfully in the experiments.
Which of the following hypotheses best accounts for the findings of the experiment?
(A) The neurons of the brain react less when a subject is trying to recognize patterns than when the subject is doing other kinds of reasoning.
(B) Those who performed best in the experiment experienced more satisfaction when working with abstract patterns than did those who performed less well.
(C) People who are better at abstract pattern recognition have more energy-efficient neural connections.
(D) The energy expenditure of the subjects brains increases when a design that completes the initially recognized pattern is determined.
(E) The task of completing a given design is more capably performed by athletes, whose energy expenditure is lower when they are at rest than is that of the general population.