2017年考研英語專項訓練題及答案

　　閲讀理解

　　篇一：

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 any, 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 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 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.

1. The author of the text 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.

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

[A] the combustion of gasoline releases photochemically active hydrocarbons.

[B] the combustion of gasoline embraces an intricate set of reactions.

[C] gasoline molecules have a simple molecular structure.

[D] gasoline is composed of small molecules.

3. The text 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.

4. Which of the following most closely parallels the situation described in the first sentence of the text?

[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 populating 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.

5. It can be inferred that the author of the text most likely regards the criticism of methanol 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.

　　[答案與考點解析]

1. 【答案】C

【考點解析】這是一道中心主旨題。本文的中心主旨句是首段的尾句。通過對首段尾句以及其它段落主題句的閲讀和理解，可以推導出本題的正確選項是C。考生在破解此類題型時一定要首先抓住原文的中心主旨句以及各段的主題句。

2. 【答案】B

【考點解析】本題是一道指代詞題型。根據題幹中的“incomplete combustion”可將本題的答案信息來源迅速確定在第二段的第四句，該句中的指代詞“these”暗示本題的具體答案信息來源應該在第二段的第三句。通過閲讀和理解第二段的第三句可推導出本題的正確選項是B。考生在解題時對指代詞一定要認真理解。

3. 【答案】A

【考點解析】本題是一道審題定位題型。通過題幹中的“air pollution”可將本題的答案信息來源迅速確定在第一段，因為第一段首句中含有“noxious pollutants”，都在談污染的問題。通過閲讀和理解第一段，尤其是第一段尾句即全文的中心主旨句，可推導出本題的正確選項是A。這是一道比較難的題。考生在解題時一定要具備審題定位能力，還要具備歸納和推導能力。

4. 【答案】C

【考點解析】這是一道類比題型，因為本題題幹中含有“parallels”(與……相當，與……一樣)一詞。本題題幹已將類比的參照對象確定在第一段的首句。通過仔細閲讀和理解第一段的首句，可推導出本題的正確選項是C，因為該選項涉及的增減關係的前提條件和原文一脈相承。考生在破解這種題型時應對原文所表達的內容與關係有明確的認識和把握，不可以無根據地推導。

5. 【答案】A

【考點解析】這是一道細節推導題型。本題題幹中的“the criticism of methanol”把本題的答案信息來源確定在第四段的第一、二句。通過閲讀和理解這兩句話，尤其是第二句話，就可推導出本題的正確選項A。考生在破解本題時一定要注意第二句話的第一個詞“Yet”在語意上所起的作用。考生在解題時一定要重視啟承轉合詞的出現和功能。

　　[參考譯文]

近年來，儘管單個機動車輛排放的有毒污染物已大幅減少，但這些機動車輛的數量一直在持續增長，結果是，在美國有100多個城市的大氣中一氧化碳、灰塵和臭氧(由車輛尾氣中的碳氫化合物經光化反應產生)的含量已超出了法定的限度。人們愈來愈認識到，實現車輛廢氣進一步減少而又不必大規模減少私家轎車的唯一有效途徑是用清潔燃料來代替傳統的柴油和汽油燃料。這些清潔燃料包括壓縮天然氣、液化石油氣、乙醇和甲醇。

所有這些替代產品都是碳基燃料，不過它們的分子要比汽油的分子小且簡單。它們可以比汽油燃燒得更徹底，部分原因在於，即使它們含有碳—碳化學鍵，含量也較少，而且它們釋放的碳氫化合物也不大可能產生臭氧。那些具有多重碳——碳化學鍵的大分子在燃燒時包含了一系列複雜的反應。這些反應增大了不完全燃燒的可能，並且更容易釋放未燃燒的碳氫化合物，而這些化合物又對光化學反應很活躍。另一方面，這些替代燃料也有自己的缺點。壓縮天然氣可能需要車輛配備一個笨重的油箱，這對車輛性能和燃料效率又極為不利，並且液化石油氣還面臨着供應上的根本限制。

從另一方面來看，甲醇和乙醇與其它的碳基替代燃料相比有重要的益處：它們具有單位體積更高的能量含量，而且對現存的燃料銷售網絡只需很小地改變。乙醇通常作為汽油的替代品，但目前它比甲醇要貴兩倍，因此甲醇的低廉價格便成為引人注目的特點。然而，甲醇最吸引人的特點還在於它可以減少90%形成臭氧的廢氣，而臭氧又是城市中最嚴重的污染物。

和其它的替代燃料一樣，甲醇也遭到了非難。可大多數批評都建立在使用“汽油系列”的車輛不進行最簡單的設計改進以可能使用甲醇燃料的基礎上。例如，事實上一定體積的甲醇和同體積的汽油和柴油相比，只能提供相當於它們大約一半的能量。在其它因素相同的條件下，油箱可能要大一點和重一點，然而，由於甲醇燃料的車輛可以設計得比使用甲醇的“汽油系列”車輛還要高效，它們可能需要更少的燃料。同時，對發動機進行最簡單的改進便可使用甲醇的車輛，這將對城市大氣污染的迅速減輕做出貢獻。

　　篇二：

One of the simplest and best known kinds of crystal is the ionic salt, of which a typical example is sodium chloride, or ordinary table salt. The fundamental components of an ionic salt are ions: atoms or molecules that have become electrically charged by gaining or losing one more electrons. In forming sodium chloride, for example, sodium atoms give up an electron (thereby becoming positively charged) and chlorine atoms gain an electron (thereby becoming negatively charged). The ions are attracted to one another by their opposite charges, and they stack together compactly, like tightly packed spheres.

Recently, scientists at Michigan State University created a new kind of crystal called an electride. In electrides, the anions (negative ions) are completely replaced by electrons, which are trapped in naturally formed cavities within a framework of regularly stacked cations (positive ions). Electrides are the first examples of ionic salts in which all these anionic sites are occupied solely by electrons.

Unlike other types of anions, anionic electrons do not behave as if they were simple charged spheres. In particular, because of their low mass and their tendency to interact with one another over great distances, they cannot be “pinned down” to any one location. Instead, they wander close to and among the atoms lining the cavity and interact with electrons in nearby cavities, perhaps changing places with them.

The properties of an electride depend largely on the distance between the cavities that hold trapped electrons. When the trapped electrons are far apart, they do not interact strongly, and so behave somewhat like an array of isolated negative charges. When they are closer together, they begin to display properties associated with large ensembles of identical particles. When they are still closer, the ensemble properties dominate and the electrons “delocalize”: they are no longer tightly bound within individual cavities but are more or less free to pass through the spaces within the framework of positive ions.

By synthesizing electrides from a variety of materials, one can vary the geometry of the anionic cavities and their relation to the surrounding cations. The resulting properties may make it possible for electrides to become a basis for economically useful new materials and devices. For instance, because the electrons in some electrides are very weakly bound, these crystals could be effective as photosensitive detectors, in which an impinging photon liberates an electron, resulting in a small electric current. The same weak binding could also make electrides useful in solar energy converters and as cathodes in batteries. One obstacle is the tendency of electrides to decompose through reaction with air and water. Researchers are seeking ways to increase their stability.

1. The text is primarily concerned with discussing

[A] a way to isolate electrons.

[B] the characteristics of a new kind of crystal.

[C] the structure of an ionic salt.

[D] commercial uses for electrides.

2. In the first paragraph, the author is primarily concerned with

[A] introducing a variant on the standard atomic theory.

[B] describing how chlorine atoms can become negatively charged.

[C] describing some early research at Michigan State University.

[D] providing background for the technical discussion to follow.

3. According to the text, the defining characteristic of an electride is which of the following?

[A] Its positive are of particularly low mass.

[B] Its ions possess identical electrical charges.

[C] It contains a framework of regularly stacked ions.

[D] Its negative ions consist solely of electrons.

4. It can be inferred from the text that anions behaving as “simple charged spheres” (line 2, paragraph 3) could be expected to

[A] readily lose electrons and become positively charged.

[B] move freely in and out of their cavities.

[C] respond to photons by liberating electrons.

[D] remain fixed relative to their cations.

5. With which of the following statements regarding electrides would the author most likely agree?

[A] They have proven themselves to be of great commercial value.

[B] Their future commercial value is promising but uncertain.

[C] They are interesting but of no practical value.

[D] They have commercial value mainly in solar energy applications.