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新加坡，一个美丽的国家。但本篇着重介绍新加坡花费大量财力建筑立交桥，以及它们的利弊。最终得出结论，人们应该使用立交桥因为它们对防止交通事故的发生起很大的作用。
答案简析
1.B。本句是定语从句中的第二个小分句，做时特别要注意。意为“在交通拥挤和过马路不太安全的地方”。
2.A。make sb. do sth. 其它词性不对。
3.A。“效率高”与“不方便”意思上相反,故用though，有“尽管”的意思。
4.B。 pass与bridge无法搭配,而visit ,build与bridge搭配意思不符。
5.C。繁忙的马路。
6.B。why引导表语从句，意为“这就是……的原因”。
7.C。建造立交桥.。
8.C。keep … doing 意为“让……一直干某事” 。
9.B。spend…(in) doing 意为“在建立交桥上花费了大量的财力”。
10.D。建立交桥一方面有利安全，另一方面帮助人们。所以人们应该使用它们，而不是横穿马路(有如在建立交桥之前)。instead of “而不是”，“代替”。
11.A。 老人上下立交桥当然是有点困难，difficult形容词作宾语补足语。
12.D。指过去没有立交桥时，既有人又有车辆过马路，with“伴有”，“带有”。
13.A。两者都(老年人和年轻人)。
14.B。建议人们应经常使用立交桥，其它选项在意思上都不对。
15.D。固定短语stop sb. from doing，本句意为“阻止交通事故的发生。
The water and the land are thought part of the earth surface (表面). The air is 1_ thought a kind of blanket (毯子) 2_ the earth. But it is 3_ than that. Maybe you have been in a cave (洞穴) 4_ in the earth. Did you think about the air that was in the cave? The land has some air mixed in it. Air is even mixed 5_ the water in the sea. These examples show that some air is 6_ the earth’s surface as well as above it.
Men once 7_ that there were four basic things from which everything else was made. They 8_ these things-earth, fire, air and water the four elements (元素). 9_ man made more observations, they 10_ that fire was not an element. 11_ they concluded (得出结论) that land, air and water were not elements, 12_ .
13_ , there are more than 100 elements from which scientists believe all things are made. 14_ land, air and water are not elements, they are three main parts of man’s environment (环境). You will 15_ more about them as you study the earth.
1. A. usually B. seldom C. never D. sometimes
2. A. above B. around C. across D. among
3. A. better B. more C. less D. worse
4. A wide B. high C. long D. deep
5. A. at B. in C. with D. to
6. A. below B. before C. between D. beside
7. A. found B. thought C. knew D. understood
8. A. called B. told C. name D. said
9. A. That B. For C. As D. So
10. A. believe B. planned C. decided D. want
11. A. End B. At last C. Hardly D. Nearly
12. A. too B. neither C. also D. either
13. A. True B. Read C. In fact D. Correctly
14. A. When B. As C. Since D. Though
15. A. exam B. study C. exercise D. know
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