用所给词的适当形式填空，每空不限一词。
1. I think it's __________ (use) to talk with him. It's difficult to change his mind.
2. Did you have a nice time __________ (ski) last week?
3. Our teachers told us that the earth __________ (move) around the sun.
4. __________ (wolf) eat smaller animals when they are hungry.
5. __________ (luck), he didn't hurt badly.
6. His grandpa is ill. He was even __________ (ill) this morning.
7. When I saw the squirrels, I became __________ (interest) in them.
8. Can you teach me how __________ (dance)?
9. I __________ (drive) to Beijing when my car broke down.
10. Don't leave the baby by __________ (he). It's not safe to leave him alone at home.
