modals of obligation

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• I have to get up at seven every day.​

• ​She has to speak English at work.

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• ​We don't have to wear a uniform at school.

• ​He doesn't have to work on Saturdays.

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• ​Do I have to buy a grammar book?

• ​What time does she have to get up in the morning?

[+]: sub + have to, has ,to , had to + verb(inf)

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​[-]: sub + don't, doesn't , didn't + have to + verb(inf)

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​[?]: Do, does, did + sub +have to + verb(inf)

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​[?]: Qw + do, did,does + sub +have to + verb(inf)

Use

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1. Use have to + verb(inf) to talk about rules and obligations. 

2. ​​​Use don't have to + verb(inf) to say that there is no obligation

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Don't contract have or has :

• ​I have to go 

• I've  to go

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​ Must/Mustn't / Can't

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• You must do your homework tonight​.

• ​She must clean up her room before she goes out.

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• ​You must not leave you bag here.

• ​You can't bring food into the library.

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​[+]: sub + must + verb(inf)

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​[-]:sub + mustn't/can't + verb(inf)

1. ​We use must to talk about rules and obligations.

3. ​Use can't to talk about something that is prohibited.

5. ​The verb must is not often used in questions.

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​Have to and must have the same meaning 

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​She must attend the class

​She has to attend the class

​Mustn't and don't have to don't have the same meaning.

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• ​ You mustn't drive fast. It's a school area

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• ​You don't have to drive fast we still have time

• ​You should wear a suitcase to the interview.

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• ​He's very stressed, he shouldn't work so hard.

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• ​You shouldn't drink coffee in the evining.

• ​We use should/ Shouldn't to give a piece of advice or to tell someone what's better for them to do.

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• ​Say I think you should or I don't think you should

• ​Don't say I think you shouldn't