Here are the sentences filled in with "used to" and appropriate verbs:

1. When I was a child, I **used to climb** trees in the park.
2. They **used to have** a pet dog named Max.
3. She **used to play** the piano for hours every day.
4. We **used to go** on family vacations to the beach.
5. He **used to eat** ice cream every Friday after school.
6. My grandparents **used to live** in a small village.
7. I **used to watch** cartoons on Saturday mornings.
8. They **used to visit** their grandparents every summer.
9. She **used to dance** ballet when she was younger.
10. We **used to have** picnics in the park on sunny weekends.