公共英语考试三级阅读理解模拟题：
　　Greenhouse Effect
　　A greenhouse is a building made of glass which is used for keeping plants warm when the outside temperature is low.In a similar way，there are several gases in the atmosphere which trap the heat generated by the sun and prevent it from escaping.These gases are known as"greenhouse gases"，and the way in which they trap heat in the atmosphere is called the"greenhouse effect".This is not simply air pollution like photochemical smog(光化学烟雾)，for example.Most of the main greenhouse gases occur naturally in small amounts in our atmosphere，and without them the earth would be thirty degrees colder and human life would not exist.In other words，the greenhouse effect is a natural process which is to some extent beneficial to us.
　　The problem is that in the last century and a half，we have been putting excessive amounts of these gases into the earth's atmosphere by burning large quantities of coal and oil and by cutting down forests.In 1850，there were 280 parts per million of carbon dioxide(二氧化碳)in the atmosphere.Now there are 360，and this figure is expected to rise to 460 by the year 2030.We now put 24 billion metric(公制的)tons of carbon dioxide into the atmosphere every year.We have also created a group of artificial greenhouse gases that are 20，000 times more effective than carbon dioxide in trapping heat in the atmosphere.These are the chlorofluorocarbon(氟氯碳)gases，which are used in refrigerators and air conditioning systems.
　　The rapid increase in greenhouse gases is making the world warmer.The world's temperature has already gone up by half a degree this century，and the sea level has risen by ten centimeters.If the amount of carbon dioxide in the atmosphere doubles，there will probably be a rise in the earth's temperature of between 1~and 4~.This may seem a small increase，but it would be enough to cause major changes in geography and agriculture.Large areas of the world would be flooded，and some regions would become dry and unable to produce crops.It is important，too，to consider that there maybe a delay of about thirty years in the greenhouse effect.This means that we are probably experiencing only now the effect of the gases put into the atmosphere up to the 1960s.Since then，our use of these gases has greatly increased.
　　1、A small increase in the earth's temperature may bring about
　　A a decline in agriculture.
　　B a drop of the sea level.
　　C the death of all animals.
　　D a delay in the greenhouse effect.
　　参考答案：A
　　2、According to the passage，a greenhouse is built to
　　A keep the plants warm.
　　B prevent air pollution.
　　C stop the greenhouse effect.
　　D produce useful gases.
　　参考答案：A
　　3、According to the passage，chlorofluorocarbon gases differ from carbon dioxide in that
　　A they are more useful.
　　B they are much heavier.
　　C they are more efficient in making the'world colder.
　　D they are more effective in catching the heat from the sun.
　　参考答案：D
　　4、A major cause of the increase in the greenhouse gases is
　　A the burning of trees and crops.
　　B the building of many greenhouses.
　　C the burning of large quantities Of coal and oil.
　　D the flooding of large areas of the world.
　　参考答案：C
　　5、Without the greenhouse gases，the earth would
　　A become warmer.
　　B be much colder.
　　C move more slowly.
　　D move quickly.
　　参考答案：B
　　参考译文：
　　温室效应
　　温室是由玻璃制成的建筑物，当室外温度低时，用来使植物保持温暖。以类似的方式，大气中有几种气体可以捕获太阳产生的热量，防止其逸出。这些气体被称为“温室气体”，它们吸收大气中热量的方式被称为“温室效应”。例如，这不仅仅是空气污染，像光化学烟雾。大多数主要的温室气体在自然界大气中少量产生，没有它们，地球将更冷三十度，人类生命将不复存在。换句话说，温室效应是一个自然的过程，在某种程度上对我们是有利的。
　　问题是，在上个半世纪，我们一直通过燃烧大量的煤和石油以及砍伐森林向地球大气中排放过多的这些气体。1850，大气中二氧化碳的含量为百万分之280。现在有360个，这个数字预计到2030年将上升到460。我们现在每年向大气中排放240亿公吨二氧化碳。我们还创造了一组人造温室气体，在吸收大气中的热量方面，其效率是二氧化碳的20000倍。这些是氯氟碳化酶，用于冰箱和空调系统。
　　温室气体的迅速增加正在使世界变暖。本世纪世界气温已经上升了半度，海平面上升了10厘米。如果大气中的二氧化碳数量加倍，地球的温度可能会在1~4~之间上升。这似乎是小幅增长，但足以引起地理和农业的重大变化。世界大片地区将会被洪水淹没，一些地区将会变得干燥，无法生产庄稼。同样重要的是，考虑一下温室效应可能延迟大约三十年。这意味着，直到20世纪60年代，我们可能才经历进入大气中的气体的影响。从那时起，我们对这些气体的使用大大增加。
　　今天大多数人把生活看成是商业，他们的基本哲学是竞争和效率。
　　对生活的第三种态度是艺术家的态度。这里的基本哲学是“我能把它放进去吗？”个人与他的追随者的基本关系就是合作和常识。这种观点已被历史所证明，因为历史最能记住那些为追随者的利益作出最丰富贡献的人。我们调查得越多，对生活的了解越多，我们就越相信艺术态度是唯一符合人类幸福的态度。