Must / Have to / Can

vocabulary: work​

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To talk about what people can do at work

To review modals​

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1. You need good qualifications.

2. You earn a good salary.

3. You work long hours.

4. You make important decisions about people's health.

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Use CAN to talk about things that are possible/allowed. For example:

You can send me the letter by email.

(It's possible to send it by email)

Use CAN'T to talk about things that are NOT possible/allowed.

You can't talk in the exam.

(You are not allowed to talk in the exam.)

​Must is often used in written rules:

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• ​All patients must wash their hands.

​People in authority use must when they are speaking, for example, teachers, parents etc.:

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• ​You must switch off your mobile phones.

Use them to talk about rules or things that are necessary. For example:

We have to study for the exam. (It's necessary.)

She has to do her homework. (It's necessary)

You must clean your area before you leave. (It's a rule.)

You mustn't copy in the exam. (It's a rule.)

​We use have to when we say what is necessary. It is very common in spoken English:

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• ​Doctors have to work very long hours.

• ​I have to leave for work at 7. 00 am.

Must ot Have to

​Must not means something is not allowed — it is important not to do something:

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​- Students must not talk in the exam room.

​- You mustn’t smoke in here.

​Don ’t have to means something is unnecessary:

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​- Teachers don’t have to wear a uniform.

​- He doesn’t have to work because he’s rich.

​Can means something is allowed:

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​- You can take a one—hour lunch break.

​- You can borrow up to five books from the library.

We use it to talk about something that is not necessary but is possible or allowed. For example:

You don't have to do extra work. (It's not necessary to do extra work, but if you want to you can do it).

She doesn't have to buy the book. (It's not necessary to buy the book but you can do it.)

​It means not allowed / not possible:

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​ - You can’t smoke here.

​ - Bankers can’t relax for a minute.

​1. He must be very responsible.

2. He must wear a uniform.

3. He has to have a lot of training.

4. He has to travel very far.

5. He must take his passport to work.

6. He has to sit in the cockpit of an airplane.