The key to exercise solutions in chapter Unit 32 - must / mustn't / needn't for the textbook English Grammar in Use with authors Raymond Murphy from Cambridge University Press
Question
Are these sentences OK? Change them where necessary.
Answer
We don't need to hurry.
OK
You needn't shout. / You don't need to shout. / You don't have to shout.
I didn't need to go out. / I didn't have to go out.
OK
You needn't lock the door. / You don't need to lock the door. / You don't have to lock the door.
I didn't need to say anything. / I didn't have to say anything.