1. You mustn't behave this way.
2. I must do this work.
3. Kate must be here in three hours.
4. People must take care of nature.
5. Must you leave tomorrow?
1. The car broke down so I had to go by bus.
2. I have to visit my doctor.
3. Yesterday he had to help his sister.
4. You don't have to eat it.
5. Do I have to wait for him?