练习：把下列句型改成否定形式 1. I am a teach。
2. We have two new friends.
3. She can swim.
4. They’re playing football.
5. She goes to school at seven.
6. There’s a pen in the pencil-box.
7. I like reading books.
8. Tom is interested in singing..
9. My sister can dance.
10. She likes apples.
11. Mary sings very well.
12. This is his book.
13. We call it a joey.
14. I go to the park on Sundays.
15. Her brother can play basketball.
16. There are some books on the desk.
17. Today is Sunday.
18. My oranges are orange.
19. He is eleven.
20. Li Yan has a little doll.