obligation and necessity

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Obligation and necessity

• Miss María Ruth Castillo Ubillús

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What we learn today?

Indicate obligation and prohibition

State absence of obligation

Establish an internal or external obligation

Improve your vocabulary related to transport.

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MUST – HAVE TOSomething is necessary or

obligatory.

MUST NOT – DON’T HAVE TO

Internal and external obligation.

OBLIGATION AND NECESSITY

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MustPersonal feeling.

Internal obligation. It comes from the person speaking.

I must pay attention to certain things.You must take a few minutes to familiarize yourself with the car. I must get up early tomorrow. There are a lot of things I want to do.

AUXILIAR Y VERB:

OBLIGATION AND NECESSITY

subject

auxiliary verbmust

main verb

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Have toNot personal feeling.

It is impersonal.The obligation comes for some other

person.

You have to get used to the rules.

The sign has to show the direction that the different roads to take you.

subject

auxiliary verb

main verb

to

OBLIGATION AND NECESSITY

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MUST NOT

suggest that you are prohibited from doing something

DON’T HAVE TO

suggest that someone is not required to do something

You mustn’t park on double yellow lines.

subject

auxiliary verb: must

main verb

not

IT IS FORBIDDEN, IT IS NOT ALLOWED.

PROHIBITIONMusn´t vs . have to and don’t have to

Internal and external obligation

You must not eat that.

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PROHIBITION

There’s a free space. You don’t have to pay.

You don’t have to eat that.

subject not

auxiliary verb: do

main verb

YOU CAN IF YOU WANT TO, BUT IT IS NOT NECESSARY.

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OBLIGATION AND NECESSITY

The obligation comes for some other person.

I have to get early tomorrow. I start working at 7.30 am.

subject

auxiliary verb: have

main verb

to

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HAVE TO it is followed by infinitive

HAS TO is used for the third person

DO/DOESare used for the interrogative and negative forms.

DON’T HAVE TO

we use don’t have to say that there’s no obligation to do something.It isn’t necessary. You have a choice.

He doesn’t have to drive so slowly.

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Interrogative form

Mustn’t you park in yellow lines?

Do you have to pay?

ExampleHow do you have to get out of the roundabout?

must

not

subject

main verb

haveauxiliary

verb subject main verb

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