用所给单词的适当形式填空。

1. Look, the girls ______________ (sing) now.

2. Peter ______________ (want) ______________ (write) a letter to his friend.

3. Would you like ______________ (join) ______________ (we)?

4. There is a lot of ______________ (rain) here.

5. What ______________ (do) she usually do? She usually ______________ (catch) insects.

6. They ______________ (have) a picnic this weekend.

7. I like ______________ (swim) very much.

数据库管理系统的缩写是_________。