In the past, man did not have to think about the protection of his environment. There were few people on the earth, and natural 36 seemed to be unlimited. Today things are 37 . The world has become too 38 . We are 39 our natural resources too quickly, and at the same time we are 40 our environment with dangerous chemicals. If we 41 to do this, human life on earth will not 42 . People realize today that if too many 43 are taken from the sea, there will soon be none left. Yet, with modern fishing 44 , more and more fish are caught. We know that if too many trees are cut down, 45 will disappear and nothing will 46 on the land. Yet, we continue to use bigger and more powerful machines to 47 more and more trees. We realize that if rivers are polluted with waste products from factories, we will die. 48 , in most countries waste products are still put into rivers or into the sea, and there are few laws to 49 this. We also know that if the 50 of the world continues to rise at the present rate, in a few years, there won't be enough food. What can we do to solve the 51 ? If we eat more vegetables and less 52 , there will be more food available for everyone. Land that is used to grow crops feeds five times more people than land where animals are kept. Our natural resources will 53 longer if we learn to recycle them. The world population will not 54 so quickly if people use modern methods of birth control. Finally, if we 55 people to think about the problems we shall have a better and cleaner planet in the future. 小题1: A．resources B．sources C．materials D．matter 小题2: A．common B．the same C．changeable D．different 小题3: A．crowded B．polluted C．dirty D．busy 小题4: A．producing B．using up C．reducing D．making 小题5: A．protecting B．saving C．polluting D．fighting 小题6: A．try B．continue C．stop D．have 小题7: A．live B．last C．continue D．survive 小题8: A．fish B．seagulls C．crocodiles D．frogs 小题9: A．poles B．boats C．methods D．ideas 小题10: A．mountains B．the sea C．crops D．forests 小题11: A．grow B．plant C．save D．cut down 小题12: A．plant B．cut down C．save D．burn down 小题13: A．Thus B．However C．Generally speaking D．Therefore 小题14: A．encourage B．neglect C．stop D．wake up 小题15: A．production B．pollution C．population D．revolution 小题16: A．pollution B．environment C．questions D．problems 小题17: A．fruit B．meat C．fish D．grain 小题18: A．use B．stay C．keep D．last 小题19: A．raise B．rise C．run D．grow 小题20: A．force B．help C．educate D．show