单选题 There was one thought that air pollution affected only the area immediately around large cities with factories and heavy automobile traffic. At present, we realize that although these are the areas with the worst air pollution, the problem is literally worldwide. On several occasions over the past decade, a heavy cloud of air pollution has covered the east of the United States and brought health warnings in rural areas away from any major concentration of manufacturing and automobile traffic.
In fact, the very climate of the entire earth may be infected by air pollution. Some scientists consider that the increasing concentration of carbon dioxide in the air resulting from the burning of fossil fuels (coal and oil) is creating a "greenhouse effect"—conserving heat reflected from the earth and raising the world's average temperature. If this view is correct and the world's temperature is raised only a few degrees, much of the polar ice cap will melt and cities such as New York, Boston, Miami, and New Orleans will be in water.
Another view, less widely held, is that increasing particle matter in the atmosphere is blocking sunlight and lowering the earth's temperature—a result that would be equally disastrous. A drop of just a few degrees could create something close to a new ice age, and would make agriculture difficult or impossible in many of our top farming areas.
Today we do not know for sure that either of these conditions will happen, though one recent government report drafted by experts in the field concluded that the greenhouse effect is very possible. Perhaps, if we are lucky enough, the two tendencies will offset each other and the world's temperature will stay about the same as it is now. Driven by economic profits, people neglect the damage on our environment caused by the "advanced civilization". Maybe the air pollution is the price the human beings have to pay for their development. But is it really worthwhile?

单选题 As pointed out at the beginning of the passage, people used to think that air pollution ______.

A. cause widespread damage in the countryside
B. affected the entire eastern half of the United States
C. had damaged effect on health
D. existed merely in urban and industries areas

【正确答案】 D

【答案解析】[解析] 细节题。题干意为“正如文章开篇所指出的，人们过去认为空气污染”。A项意为“在农村造成了广泛的破坏”；B项意为“影响了美国的整个东部地区”；C项意为“会损害健康”；D项意为“只存在于城市和工业地区”。根据题干定位至第一句，句中提到，人们曾经认为空气污染只会影响拥有大量工厂和拥挤交通的城市区域。D项与其意思一致，故D为正确答案。

单选题 As to the greenhouse effect, the author ______.

A. share the same view with the scientist
B. is uncertain of its occurrence
C. rejects it as being ungrounded
D. thinks that it will destroy the world soon

【正确答案】 B

【答案解析】[解析] 推理题。题干意为“关于温室效应，作者”。A项意为“与科学家持有相同的观点”；B项意为“不确定它是否会发生”；C项意为“认为它是没有依据的”；D项意为“认为它会立即毁掉整个世界”。根据题干线索词the greenhouse effect‘定位至第二段，其中第三句提到if this view is correct(如果这种观点是正确的)，这里的this view即指第二句提到的温室效应理论。由此推知，作者不确定这种理论的正确性，故B为正确答案。

单选题 The word "offset" in the fourth paragraph could be replaced by ______.

A. slip into
B. make up for
C. set up
D. catch up with

【正确答案】 B

【答案解析】[解析] 释义题。题干意为“第二段中offset一词可由……代替”。A项意为“滑入”；B项意为“弥补”；C项意为“建立”；D项意为“赶上”。第四段第二句提到，也许如果我们幸运的话，这两种趋势会互相offset：，地球气温就会保持现状。这里的两种趋势即指第二段中气温上升的趋势和第三段中气温下降的趋势。由此推知，B项符合题意，即当这两种趋势互相弥补时，地球气温才会保持现状。故B为正确答案。

单选题 It can be inferred from the passage that ______.

A. raising the world's temperature only a few degrees would not do much harm to life on earth.
B. lowering the world's temperature merely a few degrees would lead major farming areas to disaster.
C. almost no temperature variations have occurred over the past decade.
D. the world's temperature will remain constant in the years to come.

【正确答案】 B

【答案解析】[解析] 推理题。题干意为“从文章中可以推断出”。A项意为“地球气温仅上升几度不会对地球上的生物造成伤害”；B项意为“地球气温仅下降几度就会给主要的农业区带来灾难”；C项意为“在过去几十年里气温几乎没有变动”；D项意为“在未来几年中世界气温将会保持不变”。第二段最后一句提到，如果地球气温只上升几度，极地冰盖将会融化，一些沿海城市会被淹没。由此推知，A项为错误论述。第三段最后一句提到，地球气温只下降几度，世界就会进入一个新的冰川时代，这会使世界主要农业区的农业生产变得艰难甚至不能继续农业生产。由此推知，B项与其意思一致，为正确论述。C、D项均未在原文中提及。因此，B为正确答案。

单选题 This passage is primarily about ______.

A. the greenhouse effect
B. the burning of fossil fuels
C. the potential effect of air pollution
D. the likelihood of a new ice age

【正确答案】 C

【答案解析】[解析] 主旨题。题干意为“这篇文章主要是关于”。A项意为“温室效应”；B项意为“矿物燃料的燃烧”；C项意为“大气污染的潜在影响”；D项意为“新的冰川时代到来的可能”。文章开篇第一段即指出大气污染的影响是全球性的；第二段指出大气污染可能会导致温室效应，使全球气温上升；第三段指出大气污染也可能会导致全球气温下降，使地球进入一个新的冰川时代；第四段进一步指出大气污染对全球气温影响的不确定性。由此推断，C项可以全面概述全文内容，而A、B、D概述比较片面，故C为正确答案。