Question

Fill in the blanks with either 'mustn't or 'needn't':

Answer 1

Needn't

Needn't

Mustn't

Mustn't

Needn't

Answer 2

1) He $\underline\bold{needn't}$ go to bed early, tomorrow is a holiday.

2) You $\underline\bold{needn't}$ warm it. I like cold coffee.

3) You $\underline\bold{mustn't}$ drive a car if you've been drinking.

4) You $\underline\bold{mustn't}$ smoke in here. It's forbidden.

5) He is very rich, he $\underline\bold{needn't}$ work hard.

Explanation :-

→ Wherever, the work is a necessity and should definitely be done, we use must and wherever, the work should never be done we use mustn't.

→ Wherever, the work is not necessarily be done, or even if done, doesn't cause any big harm, we use needn't.