Easy Word | Luyện ngữ pháp


Luyện ngữ pháp - Destination B1 ((Unit 20: Grammar - Modals 2: obligation, probability, possibility))


Obligation

Use Modal Example
Present or future obligation - must /mustn’t
- have to
- need to		 All visitors must turn off their mobile phones.
You have to/need to press 'send'.
No present or future obligation - don't have to
- don’t need to
- needn't		 You don't have to/don't need to/needn't pay to send an e-mail.
Past obligation had to Yesterday, Sam had to buy more stamps.
No past obligation - didn’t have to
- didn’t need to		 I learnt a little Italian, but everyone spoke English, so I didn't have to/didn't need to use it.

Helpful hints
In spoken English, have to is more common than must. Must is often used in written notices and instructions.
✓ 'We have to pay the phone bill today,' Rita said.
✓ Passengers must turn off all mobile phones.

Watch out!
Mustn't and don't have to do not mean the same.

✓ You mustn't do that! ( = Don't do that!)
✓ You don't have to do that. ( = You can do that if you want to, but it's not necessary.)

Form - Probability and possibility


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