Here are the answers to the sentences:
1. He **used to work** in the Twin Towers.
2. Did he **use to leave** the classroom at 4:00 pm?
3. I **used to forgive** him.
4. He **used to beat** me.
5. The teacher **used to speak** English in the classroom.
6. He **used to write** a lot.
7. She **used to spend** time in the supermarket.
8. We **did not use to play** outside.
9. He **did not use to write** five stories a day.
10. **Did she use to eat** three times a day?