完形填空：阅读下面短文，掌握其大意，然后从各题所给的四个选项中选出一个最佳答案。（共20小题，每小题1.5分） In the past, man did not have to t

完形填空：阅读下面短文，掌握其大意，然后从各题所给的四个选项中选出一个最佳答案。（共20小题，每小题1.5分）
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    46    .                    Today things are     47     , the world has bee too     48     . We are using up our natural resources too quickly, and at the same time we are　 49     our environment with dangerous chemicals. If we continue to do this, human life on the earth     50     survive.
　　Everyone    51     today that if too many fish are taken from the sea, there will soon be none left. Yet, with modern fishing     52 , more and more fish are caught. We know that if too many trees are cut down,     53     will disappear and nothing will grow on the land. Yet, we     54     to use bigger and more powerful machines to　55     more and more trees.
　　We realize that if rivers are polluted with waste products from factories, we will die.     56     , in most countries wastes are     57    put into rivers or into the sea, and there are     58     laws to stop this. We know, too, that if the　 59    of the world continues to rise at the present rate, in a few years there will not be enough 60    . What can we do to solve these problems ?
　  If  we eat more vegetables and less　 61     , there will be more food available for everyone. Land that is used to grow crops     62     five times more people than land where animals are kept. Our natural resources will　 63     longer if we learn to recycle them. The world population will not rise so quickly if people use modern methods of birth 64     .
　　Finally, if we educate people to think about the problems, we shall have a better and clearer 65    in the future.
【小题1】A．beautifulB．unlimitedC．rareD．valuable【小题2】A．monB．the sameC．changeable D．different【小题3】A．crowdedB．smallC．dirtyD．busy【小题4】A．protectingB．savingC．pollutingD．fighting【小题5】A．may notB．will notC．shall notD．could not【小题6】A．wondersB．realizesC．considerD．discovers【小题7】A．polesB．boatsC．methodsD．ideas【小题8】A  mountains     B. the sea                 C. trees                 D. forests
【小题9】A．continueB．haveC．oughtD．go on【小题10】A．growB．plantC．saveD．cut down【小题11】A．Thus B．However C．Generally speaking D．Therefore【小题12】A．stillB．evenC．alsoD．certainly【小题13】A．too manyB．a fewC．someD．few【小题14】A．productionB．pollutionC．populationD．revolution【小题15】A．housesB．vegetablesC．foodD．lives【小题16】A．fruitB．meatC．fishD．grain【小题17】A．feedsB．increasesC．suppliesD．helps【小题18】A．useB．stayC．keepD．last【小题19】A．controlB．bornC．planD．reward【小题20】A．natureB．seaC．planetD．forestB