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Lesson

We can use 'must' to show that we are certain something is true. We are making a logical deduction based upon some clear evidence or reason.

  • There's no heating on. You must be freezing.
  • You must be worried that she is so late coming home.
  • I can't remember what I did with it. I must be getting old.
  • It must be nice to live in Florida.

We also use 'must' to express a strong obligation. When we use 'must' this usually means that some personal circumstance makes the obligation necessary (and the speaker almost certainly agrees with the obligation.)

  • I must go to bed earlier.
  • They must do something about it.
  • You must come and see us some time.
  • I must say, I don't think you were very nice to him.

We can also use 'have to' to express a strong obligation. When we use 'have to' this usually means that some external circumstance makes the obligation necessary.

  • I have to arrive at work at 9 sharp. My boss is very strict.
  • We have to give him our answer today or lose out on the contract.
  • You have to pass your exams or the university will not accept you.
  • I have to send a report to Head Office every week.

In British English, we often use 'have got to' to mean the same as 'have to'.

  • I've got to take this book back to the library or I'll get a fine.
  • We've got to finish now as somebody else needs this room.

We can also use ' will have to' to talk about strong obligations. Like 'must' this usually means that that some personal circumstance makes the obligation necessary. (Remember that 'will' is often used to show 'willingness'.)

  • I'll have to speak to him.
  • We'll have to have lunch and catch up on all the gossip.
  • They'll have to do something about it.
  • I'll have to get back to you on that.

As you can see, the differences between the present forms are sometimes very small and very subtle. However, there is a huge difference in the negative forms.

  • We use 'mustn't' to express strong obligations NOT to do something.
  • We mustn't talk about it. It's confidential.
  • I mustn't eat chocolate. It's bad for me.
  • You mustn't phone me at work. We aren't allowed personal calls.
  • They mustn't see us talking or they'll suspect something.

We use 'don't have to' (or 'haven't got to' in British English) to state that there is NO obligation or necessity.

  • We don't have to get there on time. The boss is away today.
  • I don't have to listen to this. I'm leaving.
  • You don't have to come if you don't want to.
  • He doesn't have to sign anything if he doesn't want to at this stage.
  • I haven't got to go. Only if I want to

Comments

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11:46 PM Jul 01 2009 | Reply

Miss_gorgeous

Australia

TOO SIMPLE TO UNDERSTAND ..

THANKS..

02:26 PM Jul 01 2009 | Reply

amgad R

Yemen

thank you for lesson

11:23 AM Jul 01 2009 | Reply

TranceSoul

TranceSoul

Poland

Oooh, now I really understand it!!

Thx!! :)

12:55 AM Jun 30 2009 | Reply

kukuka

kukuka

Ukraine

You made me think about the negative forms, thank you. Now I realize that I felt the difference while using them before but this lesson clearly explained all the nuances.

08:44 AM Jun 21 2009 | Reply

thekrayat

thekrayat

Jordan

thanks alot

those lesson are helped me but I think those lesson are not complete Any way thank you. Smile

01:24 AM May 31 2009 | Reply

sreyleap

Cambodia

now i can see about must/have to,but is not clearly yet.any way thank for your lesson.i'll try to learn more about it.

05:10 AM May 30 2009 | Reply

marwa_fj

marwa_fj

United Arab Emirates

It is really good lesson

01:07 PM May 29 2009 | Reply

marwa_fj

marwa_fj

United Arab Emirates

I like Grammer soooo much . Thanks for the lesson!

05:43 AM May 04 2009 | Reply

Bebby

Bebby

Turkey

Thank you for your knowledge 

12:46 AM May 03 2009 | Reply

sreyleap

Cambodia

thank you

10:58 AM Apr 29 2009 | Reply

manet

manet

Turkey

thank you

11:48 PM Apr 18 2009 | Reply

GoNe

Oman

this is really good topic, i liked it

 thanks .._

07:32 AM Apr 09 2009 | Reply

Luna Exoriens

Poland

Thank you for the another great lesson.

12:47 AM Mar 09 2009 | Reply

tiffintime

tiffintime

Sri Lanka

Good lesson.

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