用动词的适当形式填空。
1. It's difficult __________ (predict) the future.
2. I have a lot of books ___________ (read).
3. The police asked the old man __________ (try) __________ (recall) his address.
4. Why __________ (go) out at night?
5. The mother made the baby __________ (stop) __________ (cry).
6. She reached the top of the hill and stopped __________ (rest).
7. __________ (get) enough sleep is very important.
8. My advice is __________ (highlight) the key points in the texts.
