用括号内动词的正确形式填空。

1. The sun           (go) down earlier in winter than in summer.

2. I _____ (write) a letter to my pen-friend yesterday.

3. Miss Gao _____ (teach) the students to sing an English song now.

4. The Greens _____ (stay) at home next Friday.

5. He _____ (tell) to return his book to the library yesterday morning.

6. I' d like you _____ (meet) my parents tomorrow evening.

7. There _____ (be) a lot of great changes in China since 1949.

8. The fridge is used for _____ (keep) food fresh.