MODAL VERBS (I): Must, have to, don

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MODAL VERBS (I)Must, have to, dont
have to, mustnt
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Have to, dont have to

• () She has to get up at 7 every day.
• You have to drive on the left in the UK.
• (-) We dont have to wear a uniform.
• He doesnt have to work today.
• (?) Do we have to study this for the exam?
• Does he have to tidy his room?

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• Use have to to talk about rules and obligations,
  or to say that something is necessary.
• I have to study harder if I want to pass the
  exam.
• Muslims have to pray 5 times a day.

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Must, mustnt

• ()You must do your homework tonight.
• She must wash the dishes before she leaves.
• (-) You mustnt smoke in class.
• They mustnt leave their bags here.
• (mustnt must not)

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• Use must infinitive to talk about rules and
  obligations.
• Must is a modal verb. The only forms are must and
  mustnt.
• Must, as ALL MODALS, is ALWAYS followed by
  infinitive WITHOUT TO!!!

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Must vs. Have to

• Both indicate obligation, but theres a little
  difference.
• Its getting late. I must go now ? obligation
  from the speaker.
• Its getting late. My mum told me I have to be
  at home at 9. ? obligation from another person.

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OBLIGATION OBLIGATION
FROM THE SPEAKER FROM ANOTHER PERSON
I must go to bed. Im exhausted. I must remember to phone her tomorrow its her birthday. You have to wear a seatbelt in the car. Do you have to work on Saturdays? I had to wear a uniform when I was at school.
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No obligation/necessity dont have to.

• You dont have to come to the party if you dont
  want to.
• You dont have to pay for the photocopies, they
  are free.

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Prohibition mustnt

• Dont have to and mustnt are completely
  different. Compare
• You mustnt smoke inside a hospital. Its
  forbbiden. (Its the law)
• You mustnt drink and drive.
• You dont have to drive to the party, Ill pick
  you up. (You can drive if you want, but it is not
  necessary).