41．A．away　　　　 B．outside　　　 　C．off D．out

40．A．planes　　　 B．trains　　　 　 C．cars D．bikes

39．A．air　　　　　 B．fruit　　　　 　 C．food D．water

38．A．happy　　　　 B．fat　　　　 　 C．ill D．well

37．A．Or　　　　　 B．But　　　　 　 C．Because D．So

36．A．can　　　　　 B．can’t　　　　 C．may D．must

25. A.After　 　B.As soon as　 C.Until 　 　D.Before

No air means death．Though we 　　　(36)see it，there is air around us.　　　 (37)

air is everywhere and it gives life to every living thing．Without it we can’t live．Bad air makes people 　　(38)．We must have fresh(新鲜) 　　(39) to keep us in good health．

In the city there are a lot of people and there are too many 　　　(40) running on the road．The gas(气体) which the car sends out(排放) is made up of(组成) bad gases．Every day we breathe it in and 　　　　(41)．This makes us 　　　　(42)sick． So people should 　　　(43) door as much as they can．There are many factories，too．From the chimneys of these factories，we get the smoke usually in black colour．This kind of smoke is dangerous 　　　　　(44) our health．So in order to(为了) keep us 　　　(45)，we have to go out to the countryside to breathe more fresh air．Or we can go up hills to get more fresh air．

24. A.moon 　 　B.star 　　C.earth　 　 D.sun

23. A.Americans　 　 B.Englishmen　 　 C.Australians　 　ese

22. A.small　 　B.smaller　 　 C.big　　　D.bigger