20. ① You have saved my life ; I shall never forget it .

② Alan is trying to win a scholarship to Harvard University ; He won`t find it easy.

19. ① What a lovely baby! Is it a boy or a girl ?　 (指代婴儿)

② ---Who is knocking at the door ? --- It is me . (指代上文提到的与某一动作有联系的人)

18. ① It is Saturday today .(指时间)

　② It is sunny today. (天气)

③ It is two kilometers from our school to the railway station .(距离)

④ It is quiet in the classroom.(环境)

17. ① --- What is this ? --- It`s a bag .(用于代替指示代词)

16. ① ---Where is my pencil-box? ---It is right on your desk.(人称代词，代替前文提到的事物)

15. ----- There `s coffee and tea ; you can have ______ . -----Thanks.

　　　 A. either　　 B. each　　 C. one　 D. it

14. I like ______ in the autumn when the weather is clear and bright.

　　　 A. this　 B. that　 C. it　 D. one

13. ----Do you like ______ here ? ---- Oh, yes. The air , the weather , the way of life. Everything is so nice.

　　　 A. this　 B . that　 C. it　 D. one

12. We needed a new cupboard for the chicken . So Peter made ______ from some wood we had.

　　　 A. it　 B. one　 C. himself　 D. another

11. The　 Foreign Minister said ,“______ our hope that the two sides will work towards peace .”

　　 A. This is　 B. There is　 C. That is　 D. It is