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 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 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 profit, 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?
51. As pointed out at the beginning of the passage, people used to think that air pollution
A．caused 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
52. As to the greenhouse effect, the author
A．shares the same view with the scientists
B．is uncertain of its occurrence
C．rejects it as being ungrounded
D．thinks that it will destroy the word soon
53. The word "offset" in the second paragraph could be replaced by
A．slip into
B 1 make up for
C．set up
D．catch up with
54. It can be concluded 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 many 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
55. 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
参考译文
曾经有人认为空气污染只会影响到工厂林立、交通拥挤的大城市的周边地区。现在，人们意识到尽管这些地区空气污染可能最严重，但实际上这个问题是全球性的。在过去的l0年里，发生过几次这样的现象，空气污染产生的浓云笼罩在美国东部的上空，使人们警觉到郊区居民的健康也受到了威胁，尽管这里远离生产和交通的聚集地。事实上，整个地球的气候都会受到空气污染的影响。有些科学家认为随着化石燃料(煤和石油)的燃烧产生的二氧化碳在空气中不断聚集，“温室效应”正在产生——它会不断储存地球反射的热量从而提高地球温度。如果这一观点正确，地球温度哪怕只是升高几度，大部分极地的冰帽就会融化，纽约、波士顿、迈阿密和新奥尔良等城市就会变成一片汪洋。
另外还有一个不被广泛认同的观点是大气中某些成分的增多会阻挡太阳光，导致地球温度降低——这一结果也同样是灾难性的。气温哪怕只是降低几度也会造成一个类似的新的冰河时代，这会使农业生产面临困境，甚至许多高原农业地区无法再进行生产。现在我们还无法确切地知道上述两种情况哪一个会发生(尽管一个由专家完成的近期的政府报告表明温室效应非常有可能)。如果我们够幸运的话，也许这两种倾向会互相抵消，地球温度就可以保持不变了。，人们受金钱利益的驱动，忽略了“先进文明”对环境带来的侵害。也许空气污染就是人类为发展所付出的代价。但这样做真的值得吗? |
