15．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 actually 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 affected 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"-hold in 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 particular 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 concluded that the greenhouse effect is very possible）．Perhaps，if we are lucky enough，the two tendencies will offset （相互抵消） each other and the world's temperature will stay about the same as it is now．Driven by economic profits，people pay less attention to 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？
32．As pointed out at the beginning of the passage，people used to think that air pollutionC．
A．had a damaging effect on health
B．caused widespread damage in the countryside
C．existed only in urban and industries areas
D．affected the entire eastern half of the United States
33．As to the greenhouse effect，the authorA．
A．is uncertain of its cause
B．refuses to admit as a problem
C．shares the same view with the scientist
D．thinks that it will destroy the world soon
34．It can be concluded thatD．
A．temperature almost hasn't changed over the past decade．
B．the world's temperature will remain the same in the years to come．
C．raising the world's temperature only a few degrees would not do much harm to life on earth．
D．lowering the world's temperature only a few degrees would lead to disaster to farming．
35．This passage is mainly aboutC．
A．the greenhouse effect
B．the burning of fossil fuels
C．the possible effect of air pollution
D．the likelihood of a new ice age．
分析 本文主要写了大气污染给人类的带来的潜在的影响和对于农业造成的危害．
解答 32．C 细节理解题．由第一段第一句话There was one thought that air pollution affected only the area immediately around large cities with factories and heavy automobile traffic有人认为，空气污染只影响了周围的大城市，工厂和重型汽车交通．可推断出人们常常是这样认为，所以答案选C．
33．A 推理判断题．第一段最后一句"If this view is correct---"表明作者只是引用这种现象并不确定其正确性，可以推断出作者对于这种原因并不确定，所以答案选A．
34．D 推理判断题．根据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．仅仅几度的下降就能创造出一个接近新冰河时代的东西，这将使农业在我们的许多农业区变得困难或不可能．可推知答案选D．
35．C主旨大意题．文章是在讨论大气污染给人类带来的潜在影响．所以答案选C．
点评 推理判断题要求在理解原文表面文字信息的基础上，做出一定的推理判断，从而得到文章的隐含意义和深层意义．推理判断题所涉及的内容可能是文中的某一句话，也可能是某几句话，所以，推理题的答案只能是根据原文表面文字信息一步推出的答案：即对原文某一句话或某几句话所作的同义改写或综合．推理判断题的题干中通常含有infer，suggest，imply，conclude indicate等标志性词语． 这种题型主要包括细节判断题、态度观点推断题、写作意图推断题、文章出处判断题和猜测想象推断题．
