Pollutants coming from automobile operation have begun to cause many environmental problem

Pollutants coming from automobile operation have begun to cause many environmental problems. It has been calculated, for example, that 70% of the carbon monoxide(一氧化碳), 45% of the nitrogen oxides(氮氧化合物), and 34% of the hydrocarbon (碳氢化合物) pollution in the United States can be traced directly to automobile exhausts (废气). In addition, rubber, motor oil and other materials accumulate on roadways and are washed into streams, with effects nearly as serious as those of untreated waste water.
In an effort to improve the situation, the U.S. government has made regulations on the use of the constituents (成分) of automobile exhaust gas that are known to cause air pollution. These constituents fall roughly into three types: hydrocarbons that pass through the engine unburned; carbon monoxide, also a product of incomplete burning; and nitrogen oxides which are formed when nitrogen and oxygen are in contact at high temperatures. Besides their own poisonous character, hydrocarbons and nitrogen oxides react in the presence of sunlight to form harmful smog. Carbon monoxide and hydrocarbons are rather easily controlled by the use of higher burning temperatures in engines. Unfortunately, the conditions that produce minimum emission of hydrocarbons tend to raise emission of nitrogen oxides. In a way this difficulty is solved by adding recycled exhaust gas to the fuel mixture, thus avoiding the oversupply of oxygen that favors formation of nitrogen oxides.
California, which has the most strict air-pollution laws in the United States, requires further special compounding of gas to control emissions, and several states have ordered that alcohol be mixed with gas, as this will reduce emissions of the carbon monoxide by 35 per cent and the hydrocarbons by 15 per cent.
【小题1】The author uses figures in Paragraph 1 .A．to reflect the rapid growth of automobile useB．to highlight the importance of environment protectionC．to show the consequence of automobile exhaustsD．to criticize the low quality of cars【小题2】How are nitrogen oxides formed according to the text?A．Nitrogen and oxygen are put together in great heat.B．Carbon monoxide and oxygen are mixed together.C．Hydrocarbons pass through the engine.D．Nitrogen is burned incompletely.【小题3】Which of the following is NOT true according to the text?A．Carbon monoxide can be controlled in the engine.B．Smog will form when hydrocarbons meet nitrogen oxides in the sunlight.C．Hydrocarbons have no poisonous character themselves.D．The conditions that decease emission of hydrocarbons will increase emission of nitrogen oxides.【小题4】According to the text, alcohol is added to gas in order to .A．increase awareness of environment protectionB．control air pollutionC．increase the fuel efficiencyD．replace gas graduallyC

(答案→)C 解析：文章介绍现在因为汽车尾气的排放，空气受到严重的污染，文章分析汽车尾气的成分和它们的危害，同时介绍解决空气污染问题的方法。【小题1】细节题：从第一段的句子：that 70% of the carbon monoxide(一氧化碳), 45% of the nitrogen oxides(氮氧化合物), and 34% of the hydrocarbon (碳氢化合物) pollution in the United States can be traced directly to automobile exhausts (废气). 可知这些数字表明汽车废气的后果，选C【小题2】细节题：从第二段的句子：nitrogen oxides which are formed when nitrogen and oxygen are in contact at high temperatures.可知 氮氧化合物和碳氢化合物是通过热量结合的，选A【小题3】细节题：从第二段的句子：Besides their own poisonous character, hydrocarbons and nitrogen oxides react in the presence of sunlight to form harmful smog. 可知碳氢化合物本身也是有毒的，选C【小题4】细节题：从最后一段的句子：states have ordered that alcohol be mixed with gas, as this will reduce emissions of the carbon monoxide by 35 per cent and the hydrocarbons by 15 per cent. 可知把酒精加入到汽油里面，是为了减少空气污染。选B

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