用所给动词的适当形式填空。

1. By the time I _____ (get) up, my brother _____ ( get, already) in the shower.

2. By the time she _____ (get) to class, the teacher _____ (start, already) teaching.

3. When she _____ (get) to school, she _____ (realize) she _____(leave) her backpack at home.

4. — _____ you ever _____ (be) late for school?

    —Yes, I have. 

    —Why _____ you late?

    —Because the bus _____ (break) down.