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| In the past, man did not have to think about the protection of his environment. There were few people on the earth, and natural resources seemed to be 1 . Today things are 2 , the world has become too 3 . We are using up our natural resources too quickly and at the same time we are 4 our environment with dangerous chemicals (化学制品). If we continue to do this, human life on the earth 5 survive. Everyone 6 today that if too many fishes are taken from the sea, there will soon be none left. Yet, with modern fishing 7 , more and more fishes are caught.We know that if too many trees are cut down, 8 will disappear and nothing will grow on the earth. Yet we 9 to use bigger and more powerful machines to 10 more and more trees. We realize that if rivers are polluted with waste products from factories, fish will die. 11 , in most countries wastes are 12 put into rivers or into the sea, and there are 13 laws to stop this. We know, too, that if the 14 of the world continues to rise at the present rate, in a few years there will not be enough 15 . What can we do to solve these problems? If we eat more vegetables and less 16 , there will be more food available (可用的) for everyone.Land that is used to grow crops 17 five times more people than land where animals are kept. Our natural resources will 18 longer if we learn to recycle (循环再用) them. The world population will not rise so quickly if people use modern methods of birth 19 . Finally, if we educate people to think about the problems, we shall have a better and cleaner 20 in the future. | ||||
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