| 燕子是一种候鸟，每年春天，它们都要从低纬度地区向高纬度地区转移。这是老幼皆知的常识。然而，古代的人们对燕子在冬天的去向一无所知。 在2400年前，古希腊的哲学家、科学家亚里士多德曾下了个结论：燕子在沼泽地带的冰下过冬。多少个世纪以来，人们把这一结论当作真理。直到18世纪，一位叫布韦的科学工作者提出质疑，并把五只燕子放进冰窖里，结果燕子都被冻死。实验证实了亚里士多德的结论是错误的。 瑞士北部有个补鞋匠，他家里飞来一只雌燕，在屋檐下筑巢，每年秋天总要飞走，补鞋匠为弄清它的去向，写了一张字条缚在燕子的跗骨上，纸条上写的是：燕子，请告诉我，你在何处过冬 第二年春天，燕子归来，补鞋匠发现有了一张新的字条，上面写着：它在雅典安托万家过冬。 这件事传开了，研究人员开始给燕子记标放飞，逐渐掌握了燕子的迁徙规律。 如果不是补鞋匠，要弄清世界各地燕子的迁徙规律不知还要晚多少年。 |
小宇一直住在哪儿
A．亲戚家
B．父母家
C．邻居家
D．奶奶家
参考答案：D
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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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