This document discusses the use of must/mustn't and have to/don't have to for expressing rules, obligations, and prohibitions. Must and mustn't are used to talk about rules and what is prohibited, while have to and don't have to refer to rules, obligations, and what is necessary or unnecessary. The document also provides examples of how to choose the correct modal verb for different situations and contexts.

1. ADULTS IV UNIT 5C
have to, don’t have to, must, mustn’t

2. MUST / MUSTN’T
+ She must tidy her room before she goes out.
- You mustn’t smoke in class
Use must+infinitive to talk about rules and obligations.
Use mustn’t+infinitive to say something is prohibited.

3. HAVE TO / DON’T HAVE TO
+ She has to get up at 7.oo everyday.
- He doesn’t have to work on Saturdays.
Use have to+infinitive to talk about rules and obligations,
or to say something is necessary.
Use don’t have to+infinitive to say there is no obligation,
or something is not necessary.

4. 1) Don’t contract have or has.
I have to go. NOT I’ve to go.
2) Must and have are very similar, but there is a
small difference. We normally use have to for a
general obligation (a rule at work). We normally
use must when the speaker imposes the
obligation.

5. Choose the correct option
You ….. smoke in this room.
A) Must
B) Mustn’t
C) don’t have to

6. Choose the correct option
I …. do my homework.
A) Must
B) Have to
C) don’t have to

7. Choose the correct option
We …. be quiet.
A) Must
B) mustn’t
C) don’t have to

8. Choose the correct option
You …. make noise in this area.
A) Must
B) mustn’t
C) don’t have to

9. Choose the correct option
You …. put the rubbish into the bin.
A) Must
B) mustn’t
C) don’t have to

10. Choose the correct option
You …. Take photos in this museum.
A) Have to
B) mustn’t
C) don’t have to

11. Choose the correct option
You …. speak on the phone on an
aeroplane.
A) Have to
B) mustn’t
C) don’t have to

12. Choose the correct option
You …. swim in this river. It’s
dangerous.
A) Have to
B) mustn’t
C) don’t have to

13. Choose the correct option
The traffic light is red. You …. stop!
A) Have to
B) must
C) don’t have to

14. MODIFIERS
 (They modify the adjective).
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