A.when B.what C.that D.where

18. _________ she did this is unknown.

　A.That B.How C.Why D.All the three

19. Take care _________ nothing happens to the baby！

　A.of that B.of what C.what D.that

20. I am lucky _______ the thing I enjoy doing most is _____ I've ended up doing.

　A.what；what B.that；that C.what；that D.that；what

二、it用法练习

1. Tom's mother kept telling him that he should work harder，but _______ didn't help.

　A.he B.which C.she D.it

2. There is a photo on the wall. _______ a photo of Lei Feng.

　A.It B.It's C.Its D.He's

3. Do you consider _________ wise to tell him the truth？

　A.that B.this C.which D.it

4. I lost my pen. I'm looking for __________ .

　A.one B.that C.it D.this

5. I glanced at my watch. _________ was earlier than I thought.

　A.There B.This C.That D.It

6. ________ is important for us to learn foreign languages.

　A.This B.He C.It D.That

7. ________ needs further discussion whether we'll build a library or not.

　A.We B.He C.It D.There

8. The Parkers bought a new house but _____ will need a lot of work before they can move in.

　A.they B.it C.one D.which

9. People in the west make _____ a rule to buy Christmas presents for their relatives and friends.

　A.it B.that C.thais D.as

10. It was she that ______ a sharp whistle，which makes ____ possible for us to catch the thief.

　A.gave off；this B.sent out；that C.gave；it D.sent；them

11. We'll go to the cinema tonight. We must book the tickets in advance. Who'd like to do ___？

　A.that B.it C.this D.one

12. ________ doesn't make any difference my being there.

　A.That B.Which C.He D.It

13. I hate _______ when people talk with their mouths full.

　A.it B.that C.these D.them

14. - Who's knocking at the door？

　　- _______ . I've come to tell you that the get-together has been put off.

　A.This is I B.It's I C.It's me D.This is me

15. _______ was December 26, 1893 _______ Mao Zedong was born in a common village.

　A.The day；when B.It；that C.It；when D.That；on which

16. Wasn't _________ a shame that she could never have any real happiness？

　A.there B.this C.that D.it

17. The beggar kept asking money form the others，but _____ didn't help him out of poverty.

　A.he B.which C.she D.it

18. The baby was crying. His mother fornd _________ hard to make him laugh.