2023-09-23 23:05:20
Further reading on the differences between of
must, mustn't and
needn't
1. The modals
must,
must not and
need not have the same form regardless the subject. There is no ending with he/she/it.
āŗ If you want to say that something is necessary or obligatory, use "must":
I must a doctor now.
āŗ If you want to say that something is less necessary, use "need":
- I need to wash my car soon.
must vs. mustn't
You must do something = it is necessary that you do it:
- Donāt tell anybody what I said. You must keep it a secret.
- We donāt have much time. We must hurry.
You mustnāt do something = donāt do it:
- You must keep it a secret. You mustnāt tell anyone. (= donāt tell anyone)
- We must be very quiet. We mustnāt make any noise.
neednāt and donāt need to
You neednāt do something = itās not necessary to do it (but you can if you want):
- We have plenty of time. We neednāt hurry. (= it is not necessary to hurry)
- Joe can stay here. He neednāt come with us. (= it is not necessary for him to come)
You can also use donāt/doesnāt need to:
- We donāt need to hurry.
Note that we say ādonāt need to doā, but āneednāt doā (without to).
āŗ However, if you want to say that something is unnecessary, use need not, not must not. (The negation of must means not allowed to.)
- I must play football. = I have to play football.
- I need not play football. = I do not need to play football. = I do not have to play football.
- I must not play football. = I am not allowed to play football.
Compare neednāt and mustnāt:
- You neednāt tell Steve. I can tell him myself. (= it is not necessary)
- You mustnāt tell Steve. I donāt want him to know. (= donāt tell him)
neednāt have (done) and didnāt need to (do)
He neednāt have done something = he did it, but now we know that it was not necessary:
- Why did he get up at 5 oāclock? He neednāt have got up so early. He could have stayed in bed longer.
He didnāt need to do something = it was not necessary to do it. It doesnāt matter whether he did it or not:
- He didnāt need to get up early, so he didnāt.
- He didnāt need to get up early, but it was a beautiful morning, so he did.
You can also say āHe didnāt have to get upā in these examples.
Although they both express an absence of necessity in the past, "didnāt need to" and "neednāt have" can have very different meanings.
When referring to an action that happened in the past that was unnecessary, it is more common in British English to use "
neednāt have done". Using didnāt need to in this way is also OK.
- You neednāt have brought dessert. (This form is more common in the UK.)
- You didnāt need to bring dessert.
However, when referring to an action that didnāt happen in the past, we can only use "didnāt need to".
- He started to feel better, so I didnāt need to call the doctor.
- He started to feel better, so I neednāt have called the doctor.
https://t.me/English_Grammar_in_Use_5th
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