Need to / Have to / Must

need to - shows an action is important and necessary.

1. (Q) What do we need to bring?
   (A) You need to have a swimsuit.
   (N) You don’t need to wear a cap.
   
2. (Q) Do we need to show ID?
   (A) Yes, you do.
   (N) No, you don’t.

have to- shows an action is important and necessary.

1. (Q) What do you have to do?
   (A) I have to clean my rooms.
   (N) I don’t have to finish today.
2. (Q) Do you have to go?
   (A) Yes, I have to. / Yes, I do.
   (N) No, I don’t (have to)

not have to - shows an action is not necessary

1. You don’t have to come.
2. You don’t have to read that.
3. You don’t have to help

must - shows an action is important and necessary.

• (Q) What must we do?
• (A) You must try harder,
• (N) You mustn’t do that again.

must not - shows an action is forbidden or should not be done.

1. You mustn’t be late.
2. You mustn’t make say that!
3. You mustn’t trust him!