1. There was a secondary school here in the
1900s.
=>There used to be a secondary school here in the 1900s.
2. We didn't get up early to catch the bus several
years ago.
=> We didn't use to get up early to catch the bus.
3. He didn't know how to study English online, but
now he can study well.
=>He didn't use to know how to study English online.
4. We often played hide and seek when we were
children.
=>We used to play hide and seek when we were children.