用所给单词的适当形式填空。

1. Sometimes my brother ______ (walk) to school.

2. My cousin often ______ (do) her homework in the evening.

3. There are white ______ (sheep).

4. Jim and Lucy ______ (be) in the same class.

5. Tom's family ______ (be) all at home.

6. This isn't ______ (I) pencil-box. It's______(she).

7. What ______ you father ______ (do)?

8. We _______ (not like) this book.

9. Mrs Green ______ (look) for her cat now.

10. Would you like ______ (go) shopping with me?

三星轮变向和滑移齿轮变向，都不属于加惰轮的轮系。