1. The document contrasts the uses of "mustn't" and "needn't" through a series of examples. "Mustn't" is used to indicate something that is prohibited or forbidden, while "needn't" suggests something that is not necessary or obligatory. A total of 20 examples are provided to demonstrate situations where either "mustn't" or "needn't" would be appropriate.

1. needn't or mustn't.
needn’t
1. You ______________ wash these fruits. I've already washed
them.
needn’t
2. You ______________ translate that. I understand what you
say.
mustn’t
3. You _____________ tell Sandra. She can't keep a secret.
4. You ______________ lend me your umbrella. I love walking
needn’t
in the rain.
5. You ___________ call me. I will call you when I get home so
needn’t
that you save some money.
6. We've got plenty of time. We _____________ leave yet.
needn’t
7. We've got plenty of time. We_____________ hurry.
needn’t
8. We _____________ walk all the way home. We can take a
needn’t
taxi.
needn’t
9. We have enough food at home. We _________ go shopping
today.

2. mustn’t
10. Tom has broken his leg. He _____________ walk a lot. It is
not good for him.
11. There's plenty of time for you to make up your mind now.
needn’t
You _____________ decide now.
12. The last bus is at eleven. I _____________ miss it or else I
mustn’t
won't be able to get home.
13. That's not a secret. You _____________ whisper.
needn’t
mustn’t
14. That's a secret. You _____________ tell anybody.
needn’t
15. Take your time. You _____________ be back before eight.
16. Jim gave me a letter to post. I _____________ forget to do
mustn’t
that.
mustn’t
17. I _____________ forget to do my homework.
needn’t
18. I know what you mean. You ____________ explain further.
mustn’t
19. I have to go now. I _____________ be late for work.
needn’t
20. I can go on my own. You _____________ come with me.
Mustn’t
vs
Can’t