用括号里的词的正确形式填空。

1. My grandpa is going to have her           (90) birthday.

2. We are looking for a student             (call)Tom.

3. While we           (wait) for the bus , a girl         (run) up to us.

4. -          you ever            (be) to Beijing?

     -Yes, I           (go) there last year.

5. We have problems                (work) out the maths problem?