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. The terrible snowstorm kept them from _____ (ski) last week.

3. My uncle will come back from London. I'm waiting for his _____ (arrive).

4. _____ (wolf) eat smaller animals when they are hungry.

5. _____ (luck), he was hurt badly.

6. His grandpa was lucky enough to stay _____ (live) during the earthquake.

7. Lushan is so beautiful that he wants to go there for the _____ (two) time.

8. We should encourage people _____ (not cut) trees any more.

9. I _____ ( drive ) to Beijing when my car broke down.

10. The young trees _____ (die) soon if you don't water them in time.