1. 汽油乙醇老G原文
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 (generated by photochemical reactions with hydrocarbons from vehicle exhaust) that exceed legally established limits. There is a growing realization that the only effective way to achieve further reductions in vehicle emissions—short of a massive shift away from the private automobile—is to replace conventional diesel fuel and gasoline with cleaner-burning fuels such as compressed natural gas, liquefied petroleum gas, 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 tanks—a serious liability in terms of performance and fuel efficiency—and 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. Methanol’s 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
(A) countering a flawed argument that dismisses a possible solution to a problem
(B) reconciling contradictory points of view about the nature of a problem
(C) identifying the strengths of possible solutions to a problem
(D) discussing a problem and arguing in favor of one solution to it
(E) 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
(A) the combustion of gasoline releases photochemically active hydrocarbons 这是结果，不是原因!
(B) the combustion of gasoline involves an intricate series of reactions
(C) gasoline molecules have a simple molecular structure
(D) gasoline is composed of small molecules.
(E) gasoline is a carbon-based fuel
19. The passage suggests which of the following about air pollution?
(A) Further attempts to reduce emissions from gasoline-fueled vehicles will not help lower urban air-pollution levels.
(B) Attempts to reduce the pollutants that an individual gasoline-fueled vehicle emits have been largely unsuccessful.
(C) Few serious attempts have been made to reduce the amount of pollutants emitted by gasoline-fueled vehicles.
(D) Pollutants emitted by gasoline-fueled vehicles are not the most critical source of urban air pollution.
(E) 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?
(A) Although a town reduces its public services in order to avoid a tax increase, the town’s tax rate exceeds that of other towns in the surrounding area.
(B) 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.
(C) Although a town’s citizens reduce their individual use of water, the town’s water supplies continue to dwindle because of a steady increase in the total population of the town.
(D) 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.
(E) 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?
(A) It is substantially less expensive than ethanol.
(B) It could be provided to consumers through the existing motor fuel distribution system.
(C) It has a higher energy content than other alternative fuels.
(D) Its use would make design improvements in individual vehicles feasible.
(E) 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
(A) be somewhat lighter in total body weight than a conventional vehicle fueled with gasoline
(B) be more expensive to operate than a conventional vehicle fueled with gasoline
(C) have a larger and more powerful engine than a conventional vehicle fueled with gasoline
(D) have a larger and heavier fuel tank than a “gasoline clone” vehicle fueled with methanol
(E) 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
(A) flawed because of the assumptions on which it is based
(B) inapplicable because of an inconsistency in the critics’ arguments
(C) misguided because of its exclusively technological focus
(D) inaccurate because it ignores consumers’ concerns
(E) invalid because it reflects the personal bias of the critics
2. 长江水稻，原文
Since the 1970s, archaeological sites in China's Yangtze River region have yielded evidence of sophisticated rice-farming societies that predate signs of rice cultivation elsewhere in East Asia by a thousand years. Before this evidence was discovered, it had generally been assumed that rice farming began farther to the south. This scenario was based both on the geographic range of wild or free-living rice, which was not thought to extend as far north as the Yangtze, and on archaeological records of very early domestic rice from Southeast Asia and India (now known to be not so old as first reported). Proponents of the southern-origin theory point out that early rice-farming societies along the Yangtze were already highly developed and that evidence for the first stage of rice cultivation is missing. They argue that the first hunter-gatherers to develop rice agriculture must have done so in this southern zone, within the apparent present-day geographic range of wild rice.
Yet while most stands of wild rice reported in a 1984 survey were concentrated to the south of the Yangtze drainage, two northern outlier populations were also discovered in provinces along the middle and lower Yangtze, evidence that the Yangtze wetlands may fall within both the present-day and the historical geographic ranges of rice's wild ancestor.
1. Which of the following, if true, would most clearly undermine the conclusion that the author makes based on the 1984 survey?
¡ Areas south of the Yangtze basin currently have less wild-rice habitat than they once did.
¡ Surveys since 1984 have shown wild rice populations along the upper Yangtze as well as along the middle and lower Yangtze.
¡ The populations of wild rice along the Yangtze represent strains of wild rice that migrated to the north relatively recently.
¡ Early rice-farming societies along the Yangtze were not as highly developed as archaeologists once thought.
¡ In East Asia, the historical geographic range of wild rice was more extensive than the present-day geographic range is.
2. Based on the passage, skeptics of the idea that rice cultivation began in the Yangtze River region can point to which of the following for support?
¡ Lack of evidence supporting the existence of rice-farming societies along the Yangtze at an early date
¡ Lack of evidence regarding the initial stages of rice cultivation in the Yangtze region
¡ Recent discoveries pertaining to the historical geographic range of rice's wild ancestor
¡ New information regarding the dates of very early domestic rice from Southeast Asia
¡ New theories pertaining to how hunter-gatherers first developed rice agriculture in East Asia
3. Which of the following can be inferred from the passage about the “southern-origin theory”?
¡ The theory is based on an unconventional understanding of how hunter-gatherers first developed rice agriculture.
¡ The theory fails to take into account the apparent fact that evidence for the first stage of rice cultivation in the north is missing.
¡ The theory was developed primarily in response to a 1984 survey of wild rice's geographic range.
¡ Reassessment of the dates of some archaeological evidence has undermined support for the theory.
¡ Evidence of sophisticated rice-farming societies in the Yangtze region provides support for the theory.
答案：CBD
3. the color of purple
长阅读是那篇关于eyes of purple(大概是这个题目)的黑人小说的，我不记得是哪个月的机经了，但那个机经里主要提到了voice，事实上我读出来的意思是新观点中提到的 critic通过分析voice得到一些有用结论，即书中对上帝God的通信不属于原来的realism流派，而属于African American的某个流派。但他对voice的focus没有帮助他分析小说的structure，而这个structure是作者关注的重点。有一道题是问了这个critic和旧观点中的critic有什么相同，我选的是他没有分析小说的structrue。还有一题，就是这个长阅读的第一题，是问的作者认为N的letter to C有什么特点，我选了mark a shift to geologically and ..... removed surrondings，但还有一个选项我很想选，大概意思是这个部分比第一眼看上去更符合小说主题/主要动机。我当时看到中机经还挺开心，但事实上这个阅读一点也不简单，机经也没说到重点上，我也没完全读懂它的大意。
