用所给动词的适当形式填空。
1. What _____ you _____ (do) while the others _____ (clean) the classroom?
2. At the moment, who _____ (help) dad in the garden?
3. Mr. Brown _____ (be) a soldier since 1984.
4. Nobody _____ (finish) the homework yet.
5. How long _____ you _____ (study) in this school?
6. Every time I _____ (want) to sleep, he _____ (make) some noise and I _____
(be) angry at that.
7. I _____ (forget) to bring my ruler, so I _____ (have) to borrow one.
8. If anybody _____ (break) the model plane, he _____ (have) to pay for it.
9. Michael _____ (be) to the zoo twice this month.
10. I _____ never _____ (see) a zebra before.
