20. C　 set an example to sb. 为某人树立榜样　 have an effect on sb. 对某人有影响

19. A　 whatever引导宾语从句，no matter what只能引导状语从句。

18. B　 If breathed in.=If it is breathed in. it指毒气，假如毒气被吸入，会导致人生病。

17. D　 尽管你不会马上就获得成功，但很值得去尝试一下。

16. C “经常或有规律地锻炼”。

80. resulted in / led to　　　 81. provides / supplies; with　　 82. pay off

写作

In the picture we can see a man, who is not realistic, lying there thinking good luck might happen to him one day.

However, an old saying goes: No pains, no gains. We all know that chances usually look upon those with favor who are ready to act. But in our society today, there are still some people living in a world of fantasy without working hard. Of course everyone wants to succeed and have a better life. We can’t imagine how a man can succeed if he never tries. So let’s try hard no matter how many difficulties and failures we will meet on the way. Only by working in a down-to-earth manner and advancing step by step, will chance and success finally come to us.

答案解析：

77. has something to do　　 78. On arriving in　　 79. write / take / put down; in case

72. weather / climate　 　73. 5.4　 　74. suggestion / advice　　 75. much　 76. including

完成句子

67. amount　 　68. eight glasses　　 69. recent / medical　　 70. 3.7　 　71. physical activities

66. Because there’s no evidence for kites and pulleys in ancient Egypt.