gre考试阅读真题解析(A)

　　Although, recent years have seen substantial reductions in noxious pollutants from individual motor vehicles, the number of such vehicles has been steadily increasing consequently, more than 100 cities in the United States still have levels of carbon monoxide, particulate matter , and ozone from vehicle exhaust) that exceed legally established limits. There is a growing realization that the only effective way to achieve further reductions in vehicle emissionsshort of a massive shift away from the private automobileis to replace conventional diesel fuel and gasoline with cleaner-burning fuels such as compressed natural gas, liquefied petroleum gas and is used especially as fuel or as raw material for chemical synthesis), ethanol, or methanol.

　　All of these alternatives are carbon-based fuels whose molecules are smaller and simpler than those of gasoline. These molecules burn more cleanly than gasoline, in part because they have fewer, if and, carbon-carbon bonds, and the hydrocarbons they do emit are less likely to generate ozone. The combustion of larger molecules, which have multiple carbon-carbon bonds, involves a more complex series of reactions. These reactions increase the probability of incomplete combustion and are more likely to release uncombusted and photochemically active hydrocarbon compounds into the atmosphere. On the other hand, alternative fuels do have drawbacks. Compressed natural gas would require that vehicles have a set of heavy fuel tanksa serious liability in terms of performance and fuel efficiencyand liquefied petroleum gas faces fundamental limits on supply.

　　Ethanol and methanol, on the other hand, have important advantages over other carbon-based alternative fuels: they have a higher energy content per volume and would require minimal changes in the existing network for distributing motor fuel. Ethanol is commonly used as a gasoline supplement, but it is currently about twice as expensive as methanol, the low cost of which is one of its attractive features. Methanols most attractive feature, however, is that it can reduce by about 90 percent the vehicle emissions that form ozone, the most serious urban air pollutant.

　　Like any alternative fuel, methanol has its critics. Yet much of the criticism is based on the use of gasoline clone vehicles that do not incorporate even the simplest design improvements that are made possible with the use of methanol. It is true, for example, that a given volume of methanol provides only about one-half of the energy that gasoline and diesel fuel do; other things being equal, the fuel tank would have to be somewhat larger and heavier. However, since methanol-fueled vehicles could be designed to be much more efficient than gasoline clone vehicles fueled with methanol, they would need comparatively less fuel. Vehicles incorporating only the simplest of the engine improvements that methanol makes feasible would still contribute to an immediate lessening of urban air pollution.

　　17. The author of the passage is primarily concerned with

　　 countering a flawed argument that dismisses a possible solution to a problem

　　 reconciling contradictory points of view about the nature of a problem

　　 identifying the strengths of possible solutions to a problem

　　 discussing a problem and arguing in favor of one solution to it

　　 outlining a plan of action to solve a problem and discussing the obstacles blocking that plan

　　18. According to the passage, incomplete combustion is more likely to occur with gasoline than with an alternative fuel because

　　 the combustion of gasoline releases photochemically active hydrocarbons

　　 the combustion of gasoline involves an intricate series of reactions

　　 gasoline molecules have a simple molecular structure

　　 gasoline is composed of small molecules.

　　 gasoline is a carbon-based fuel

　　19. The passage suggests which of the following about air pollution?

　　 Further attempts to reduce emissions from gasoline-fueled vehicles will not help lower urban air-pollution levels.

　　 Attempts to reduce the pollutants that an individual gasoline-fueled vehicle emits have been largely unsuccessful.

　　 Few serious attempts have been made to reduce the amount of pollutants emitted by gasoline-fueled vehicles.

　　 Pollutants emitted by gasoline-fueled vehicles are not the most critical source of urban air pollution.

　　 Reductions in pollutants emitted by individual vehicles have been offset by increases in pollution from sources other than gasoline-fueled vehicles.

　　20. which of the following most closely parallels the situation described in the first sentence of the passage?

　　 Although a town reduces its public services in order to avoid a tax increase, the towns tax rate exceeds that of other towns in the surrounding area.

　　 Although a state passes strict laws to limit the type of toxic material that can be disposed of in public landfills, illegal dumping continues to increase.

　　 Although a towns citizens reduce their individual use of water, the towns water supplies continue to dwindle because of a steady increase in the total population of the town.

　　 Although a country attempts to increase the sale of domestic goods by adding a tax to the price of imported goods, the sale of imported goods within the country continues to increase.

　　 Although a country reduces the speed limit on its national highways, the number of fatalities caused by automobile accidents continues to increase.

　　21. The author describes which of the following as the most appealing feature of methanol?

　　 It is substantially less expensive than ethanol.

　　 It could be provided to consumers through the existing motor fuel distribution system.

　　 It has a higher energy content than other alternative fuels.

　　 Its use would make design improvements in individual vehicles feasible.

　　 Its use would substantially reduce ozone levels.

　　22. It can be inferred from the passage that a vehicle specifically designed to use methanol for fuel would

　　 be somewhat lighter in total body weight than a conventional vehicle fueled with gasoline

　　 be more expensive to operate than a conventional vehicle fueled with gasoline

　　 have a larger and more powerful engine than a conventional vehicle fueled with gasoline

　　 have a larger and heavier fuel tank than a gasoline clone vehicle fueled with methanol

　　 average more miles per gallon than a gasoline clone vehicle fueled with methanol

　　23. It can be inferred that the author of the passage most likely regards the criticism of methanol in the last paragraph as

　　 flawed because of the assumptions on which it is based

　　 inapplicable because of an inconsistency in the critics arguments

　　 misguided because of its exclusively technological focus

　　 inaccurate because it ignores consumers concerns

　　 invalid because it reflects the personal bias of the critics

　　Paule Marshalls Brown Girl, Brownstones was a landmark in the depiction of female characters in Black American literature. Marshall avoided the oppressed and tragic heroine in conflict with White society that had been typical of the protest novels of the early twentieth century. Like her immediate predecessors, Zora Neale Hurston and Gwendolyn Brooks, she focused her novel on an ordinary Black womans search for identity within the context of a Black community. But Marshall extended the analysis of Black female characters begun by Hurston and Brooks by depicting her heroines development in terms of the relationship between her Barbadian American parents, and by exploring how male and female roles were defined by their immigrant culture, which in turn was influenced by the materialism of White America. By placing characters within a wider cultural context, Marshall attacked racial and sexual stereotypes and paved the way for explorations of race, class, and gender in the novels of the 1970s.

　　24. The passage is primarily concerned with

　　 comparing the works of three Black American authors

　　 describing common themes in Black American literature

　　 discussing an important work in Black American literature

　　 providing insights about Black American literature in the early twentieth century

　　 providing historical information about the writing of Black American novels in the second half the twentieth century

　　25. According to the passage, Hurston, Brooks, and Marshall are alike in that they

　　 did not examine the effects of White culture on their characters lives

　　 were heavily influenced by the protest novels of the early twentieth century

　　 used Black communities as the settings for their novels

　　 wrote primarily about the difficulties their characters encountered in White culture

　　 wrote exclusively about female characters and the experiences of women

　　26. The authors description of the way in which Marshall depicts her heroines development is most probably intended to

　　 continue the discussion of similarities in the works of Brooks, Hurston, and Marshall

　　 describe the specific racial and sexual stereotypes that Marshall attacked

　　 contrast the characters in Marshalls novels with those in later works

　　 show how Marshall extends the portrayal of character initiated by her predecessors

　　 compare themes in Marshalls early work with themes in her later novels

　　27. It can be inferred that the author of the passage would describe Brown Girl, Brownstones as being

　　 completely different from novels written before 1959

　　 highly influenced by novels written in the early twentieth century

　　 similar to the protest novels that preceded it

　　 important in the late 1950s but dated today

　　 an important influence on novels written in the 1970s

答案：17-27：DBACEEACCDE