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．a(chǎn)ffected 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 本文主要寫了大氣污染給人類的帶來的潛在的影響和對于農(nóng)業(yè)造成的危害．
解答 32．C 細節(jié)理解題．由第一段第一句話There was one thought that air pollution affected only the area immediately around large cities with factories and heavy automobile traffic有人認為，空氣污染只影響了周圍的大城市，工廠和重型汽車交通．可推斷出人們常常是這樣認為，所以答案選C．
33．A 推理判斷題．第一段最后一句"If this view is correct---"表明作者只是引用這種現(xiàn)象并不確定其正確性，可以推斷出作者對于這種原因并不確定，所以答案選A．
34．D 推理判斷題．根據(jù)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．僅僅幾度的下降就能創(chuàng)造出一個接近新冰河時代的東西，這將使農(nóng)業(yè)在我們的許多農(nóng)業(yè)區(qū)變得困難或不可能．可推知答案選D．
35．C主旨大意題．文章是在討論大氣污染給人類帶來的潛在影響．所以答案選C．
點評 推理判斷題要求在理解原文表面文字信息的基礎(chǔ)上，做出一定的推理判斷，從而得到文章的隱含意義和深層意義．推理判斷題所涉及的內(nèi)容可能是文中的某一句話，也可能是某幾句話，所以，推理題的答案只能是根據(jù)原文表面文字信息一步推出的答案：即對原文某一句話或某幾句話所作的同義改寫或綜合．推理判斷題的題干中通常含有infer，suggest，imply，conclude indicate等標志性詞語． 這種題型主要包括細節(jié)判斷題、態(tài)度觀點推斷題、寫作意圖推斷題、文章出處判斷題和猜測想象推斷題．
