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（资源） seemed to be 26 . Today things are 27 , the world has become too 28 . We are using up our natural resources too quickly, and at the same time we are 29 our environment with dangerous chemicals. If we continue to do this,  human life on the earth will not 30 . Everyone 31 today that if too many fish are taken from the sea, there will soon be none left.  Yet, with modern fishing 32 , more and more fish are caught.  We know that if too many trees are cut down, 33 will disappear and nothing will grow on the land. Yet, we 34 to use bigger and more powerful machines to 35 more and more trees. We realize that if rivers are polluted with waste products from factories, we will die. ___ 36, in most countries wastes are 37 put into rivers or into the sea, and there are 38 laws to stop this. We know, too, that if the 39 of the world continues to rise at the present rate, in a few years there will not be enough food. What can we do to 40 these problems ? If we eat more vegetables and less 41 , there will be more food available for everyone.  Land that is used to grow crops 42 five times more people than land where animals are kept.  Our natural resources will 43 longer if we learn to recycle them.  The world population will not rise so quickly if people use modern methods of birth 44 . Finally, if we educate people to think about the problems, we shall have a better and cleaner 45 in the future. 小题1: A．beautiful B．unlimited C．rare D．valuable 小题2: A．common B．the same C．changeable D．different 小题3: A．crowded B．small C．dirty D．busy 小题4: A．protecting B．saving C．polluting D．fighting 小题5: A．breathe B．survive C．drink D．move 小题6: A．wonders B．realizes C．considers D．discovers 小题7: A．poles B．boats C．methods D．ideas 小题8: A．mountains B．the sea C．trees D．forests 小题9: A．continue B．stop C．keep D．go on 小题10: A．grow B．plant C．save D．cut down 小题11: A．Thus B．However C．But D．Therefore 小题12: A．still B．even C．also D．certainly 小题13: A．too many B．a few C．some D．few 小题14: A．production B．pollution C．population D．pronunciation 小题15: A．work B．deal C．solve D．serve 小题16: A．fruit B．meat C．fish D．grain 小题17: A．feeds B．increases C．supplies D．helps 小题18: A．use B．stay C．keep D．last 小题19: A．control B．born C．plan D．reward 小题20: A．nature B．sea C．planet D．forest