题目：Comprehensive Exercises. Choose the best answer according to the text. Task 1 Environmental Protection Throughout history man has changed its environment in order to improve its way of life. With the tools of technology it has changed many physical features of the earth. It has turned woodlands and grasslands into farms. Man has also changed the face of the earth by cutting through mountains to build roads and railways. However, man’s changes to the physical environment have not always had beneficial results. Today, pollution of the air and water is an increasing danger to man. Each day thousands of tons of exhaust are let out from motor vehicles. Smoke from factories pollutes the air of industrialized areas. The pollution of water is equally harmful. The whole ecological balance of the sea is being broken and industrial waste has already made many rivers lifeless. Now environmental protection is more urgent than ever before. As we know, massive destruction of environment has brought about negative effects and even poses a great threat to man’s existence. We know that if the population continues to rise at the present rate, in a few years, there won’t be enough food. What can we do to solve these problems? First, if we eat more vegetables and less meat, there will be more food available. Second, our natural resources will last longer if we learn to recycle them. Third, the world population will not rise so quickly if people pay attention to birth control. Last but not least, laws on environmental protection should be put into practice and enforced strictly. In a word, if we realize the seriousness of the problem and try our best to protect our environment, we shall have a better and cleaner planet in the future. How has man changed the face of the earth?
A. By burning down forests.
B. By building houses and roads.
C. By polluting rivers.
D. By cutting through mountains.
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