MUST, HAVE TO AND NEGATIVE FORMS

  MUST (obligation)

                    

                                                                                                                                   

            Self imposition or to others. Very strong advice

STRUCTURE

      ( +) SUBJECT + MUST + INFINITIVE VERB (without TO) + C

      (-)   SUBJECT + MUSN'T/ MUST NOT + INFINITIVE VERB  (without TO)

      (?)   MUST + SUBJECT + INFINITIVE VERB  (without TO)?

• 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.

•      MORAL OBLIGATION, OPINION

                to say what you think is necessary, or to recmmend someone to do something

                I haven't spoken to Sue for ages. I must phone her (I say this is necessary)
                Mark is a really nice person. You must meet him (I recommend this)

•       I NEED TO DO SOMETHING 

                I'm very hungry.  I must eat something
                It's a fantastic film. You must see it
                The windows are very dirty. We must clean them

•       IS OFTEN USED IN WRITTEN RULES AND INSTRUCTIONS

                Applications for the job must be received by 18 May  
                You must write your answers in ink (exam instruction)
             
                EXERCISE 1
                EXERCISE 2
                EXERCISE 3

MUSTN'T(prohibition)

     

• We use must not to say that something is not permitted or allowed, for example:

           Passengers must not talk to the driver.

• Must not expresses prohibition - something that is not permitted, not allowed. The prohibition can be subjective (the speaker's opinion) or objective (a real law or rule).

          Look at these examples:

          I mustn't eat so much sugar. (subjective)
          You mustn't watch so much television. (subjective)
          Students must not leave bicycles here. (objective)
          Policemen must not drink on duty. (objective)

• It's necessary that you do not do it (so don't do it). It's the wrong thing to do.

         You must keep it a secret. Yo musn't tell anyone (don't tell anyone)
         I promised I would be on time. I musn't be  (I must be on time)
         You musn't touch the pictures (don't touch the pictures)

• We can use must not to talk about the present or the future:

           Visitors must not smoke. (present)
           I mustn't forget Tara's birthday. (future)

• We cannot use must not to talk about the past. We use other structures to talk about the past, for example:

         We were not allowed to enter.
          I couldn't park outside the shop.

          EXERCISES- MUST OR MUSN'T
          ANSWERS

SHOULDN'T (prohibition)

Moral prohibition or light advice.

You shouldn't the new film- it's terrible!

You shouldn't throw banana skins on the ground floor

HAVE TO (obligation)

       

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

         The speaker is not giving his/her own opinion

           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.

            I have to work from 8.30 to 5.30 every day (a fact, not an opinion)

• 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.

• I have to do something so it is necessary to do it, I am obliged to do it

          You can't turn righ here. You have to turn left
          I have to wear glasses for reading

• Use have to with will and might or may

          If the pain gets worse, you'll gave to go to the doctor
          I might/may have to work late tomorrow evening

• We use do/does/did in question and negative sentences (for the present and past simple)

           What do I have to do get a new driving licence? (not What have I to do?)
           Karen doesn't have to work Saturdays ( not Karen hasn't to)

EXERCISE 1

DON'T HAVE TO (no obligation)

   

We use have to to talk about strong obligation that comes from somewhere else, for example from you boss, you parents, a rule at school or work.         I have to be home by ten. (My parents told me so.)         I must be home by ten. I have a very difficult day tomorrow. (It is my own decision.)        I have to get up early, because I start work at 8. (It is a rule.)        I should get up early. (Now I stay in bed until lunchtime.) Don't have to means that there isn't any obligation at all, there is no need to do it.           You don't have to tell him, but you can if you want to           I don't have to be at the meeting, but I think I'll go anyway Don't have to is different from shouldn't and mustn't.           I don't have to get up early at weekend.         (I can stay in bed as long as I want.)         You mustn't tell lies. (It is very bad to tell lies.)         You don't have to go with me.         (You can go with me if you want to.)          You shouldn't smoke. (It is bad for your health.) In spoken British English you can also use haven't got to.          I haven't got to take my sister to school, my parents do it. FORMAL ENGLISH: do(es)n't have to         EXERCISES-MUST OR HAVE TO         EXERCISE 2- MIX         EXERCISE 3- MIX SHOULD Correct behavier)  or OUGHT TO Less strong advice. MORAL OBLIGATION. You should go: an old person needs your seat ADVICE You should watch the new film- it's fantastic! DEDUCTION Level of possibilities Must: high level or possibility. In fact. No doubt It must be John ("it"a person knocks the door) May: permission(given or request)           under possibility.It's not very sure           It's sometimes absolute possibility It may be John Might: some doubt. It's not very sure might it's better than may It might be John Can't: zero possibilities I can't be John (the person is wearing a skirt)