阅读短文，按要求完成短文后的各项任务
In the past, man did not have to think about the protection of the environment. There were few people on the earth, and natural resources(资源) seemed to be unlimited(无限的) .
Today things are different, the world has become too crowded. We are using up our natural resources too quickly and at the same time we are polluting our environment with dangerous chemicals (化学制品). If we continue to do this, human life on the ①_______ will ②_______ survive.
Everyone realizes today that if too many fish are taken from rivers and the sea, there will soon be none left. Yet, with modern fishing methods(方法) , more and more fish are caught. We know that if too many trees are cut down, forests will disappear and nothing will grow on the earth. Yet we continue to use bigger and more powerful machines to cut down more and more trees.
We realize that if rivers are polluted with waste products from factories, fish will die. However, in most countries wastes are still put into rivers or the sea, and there are few laws to prevent this. Also, weknow that if the population of the world is becoming larger and larger, in a few years there will not be enough food. What can we do to solve these problems?
If we eat more vegetables and less meat, there will be more food available for everyone.
③Our natural resources will last 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 control.
Finally, if we educate people to think about the problems, we shall have a better and cleaner planet in the future. In a word, it is very important to protect our environment.
在①、②空白处分别填入一个适当的词使句意完整、上下文通顺。
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把③句译成中文。
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回答问题: How can we protect fish?
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在文中找出与There are more and more people in the world.意思相近的句子。
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在文中找出最能表达该短文主题的句子，并将它写在答题卡上。
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