The document discusses different modal verbs used to express obligation, prohibition, absence of obligation, and advice in English. Must and have to express obligation or strong recommendation, with must used for the speaker's own feelings and have to used for stating facts. Must can only be used for the present and future, while have to can be used in all tenses. You mustn't is used to express prohibition. You don't have to means there is no obligation. Should and ought to are used to give advice or opinion.

1. MODALS OF OBLIGATION
MUST, HAVE TO, SHOULD, OUGHT TO

2. OBLIGATION or STRONG
RECOMMENDATION
We use must (do) and have to (do) to say that it is
necessary to do something.
e.g. Well, it’s 11 o’clock. I must/have to go now, I have a
meeting at 11,30.

3. There is sometimes a DIFFERENCE between must and
have to.
- With MUST the speakers are giving their own
feelings, saying what they think is necessary:
e.g. I must send an e-mail to Liz. I haven’t written to her
since Christmas.
e.g. I must study English if I want to pass the exam.
- With HAVE TO the speakers are not giving their feelings.
They are just giving facts :
e.g. I can’t come on Saturday, I have to work.
e.g. Students have to wear uniforms at this school.

4. BUT, NOTE:
You can only use must to talk about the present and
future:
e.g. We must go now.
e.g. You must be on time tomorrow
Have to, however, can be used in all forms :
e.g. I had to leave the party early because I felt ill.
e.g. What do I have to do to get a degree in Economics?

5. Keep fit
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6. You must
keep fit!
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7. Put the rubbish in the bin
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8. You must put
rubbish in the bin!
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9. Speak English in class
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10. You must speak
English in class!
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11. Pay taxes
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12. You have to
pay taxes!
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13. Have a passport to
travel to Africa
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14. You have to
have a passport
to travel to
Africa!
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15. Wear a uniform
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16. They have to
wear a uniform!
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17. PROHIBITION
You mustn’t do something means it is prohibited that you
do it.
e.g. You mustn’t tell anyone what I said.
e.g. You mustn’t smoke.

18. Eat junk food
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19. You mustn’t eat
junk food!
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20. Use your phone
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21. You mustn’t use
your phone!
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22. Sleep in class
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23. You mustn’t
sleep in class!
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24. ABSENCE OF OBLIGATION
You don’t have to do something means it is not necessary
to do it.
e.g. I can stay in bed tomorrow because I don’t have to go
to school.

25. Get up early at the weekend
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26. You don’t have to
get up early at
the weekend!
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27. Work on holiday
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28. You don’t have to
work on holiday!
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29. ADVICE or OPINION
We use should (do) and ought to (do) to give advice or say what
you think is a good or a bad thing to do.
e.g. You shouldn’t smoke so much.
e.g. That cyclist should be wearing
a helmet.
* Should and ought to are very similar, and can often replace each
other. But should is much more frequent than ought to.

30. Take warm clothes if you go to Dublin
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31. You should take warm clothes if you go to
Dublin in winter!
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32. Drink so much coffee
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33. You shouldn’t drink so much coffee!
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