Must Not vs. Need Not

Must and need are modal auxiliary verbs. Must expresses ideas as such as strong obligation, compulsion etc. Need expresses ideas such as necessity. Must not shows prohibition. Need not shows lack of obligation or necessity.

Fill in the blanks with must not or need not.

Answers

1. You must not invite Sabu. I don’t want him to come.
2. You needn’t invite her. She won’t come.
3. You must not tell anybody about my decision. It is a secret.
4. You must not make a noise. The baby is sleeping.
5. You needn’t reserve a table. It is not very busy in the morning.
6. You must not quit this job before you find another one.
7. You must not waste your time on idle pursuits.
8. Those who have already registered needn’t register again.
9. You needn’t rush. You can take your time.
10. You needn’t have told her. She already knew about it.
11. You must not waste food.
12. You needn’t have cooked so much food. Nobody was hungry.