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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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