Page 79 - PDF_Oxford Grammar for Schools 5_Neat 1

Necessity and obligation

I can use modal verbs to talk about necessity and obligation.

Must,hove to, needto, can

chose som¿ library books for you. at the Library. J

f you. fveeduv't have doi<ve that! "Tfoat was teCi/vd. ThaÿOe y

That's OK. had to 00 to the library, anyway. J
(

you m.usi coiÿe tÿv ai/vd have a drifvte!

No, thai-vtes. I c-auv't. I've got to 0o hom.e ÿvow.

We use the modalverbs must,have to, can and need We use should and shouldn't to give advice or suggest
to + the infinitive when we talk about necessity, action for other people.It expresses an opinion.
obligation and freedom to act now and inthe future. Ithinkheshouldask a friendfor help.
You shouldn't eat that.
Obligation and necessity Prohibition
(= Do this.) (= Don'tdo this) We use have to to talk about rules.
has to wear black shoes for school.
must need to mustn't
should havegot to shouldn't We also use have to when a situation means that
have to can't there is no other choice for action.
We haveto climb over the wall becausethere isn'ta gate.
No obligation/necessity Permission/freedom
(= It's not important to do (= It's OK to do this.) We use need to to talk about things that are
this.) personally important, necessary or urgent.
Ineedto go now.Mybusleaves atsix.
don'thave to can, may
don't need to Have got to is similar to need to, but it is more
needn't
informal and also more urgent.
Is that the time? I'vegot to go!
We use must, mustn't and can't to talk about rules
and to give orders. We've got to tell the teacher about this.
You must stop at theyellow line. When there is no obligation or necessity we use
You mustn't runwith the ball. don't haveto, don't need to and needn't.
We can't talk inthe library. Idon'tneedto get upearly tomorrow-it'sthe first day
ofthe schoolholidays!
We also use must and mustn't to give ourselves and
You needn't worry about that.
others strong advice.
I must remember to bringsome water. When we ask about obligation we use Do/Does...
You mustn't worry so much! have to...?
Doyouhaveto do homework everyday?
We use can and may to say that something is
permitted.May is moreformal than can. When we ask about specific necessity we use
You canleaveyour bookson the shelfthis evening. Do/Does ...need to...?
DoI needto bring this book tomorrow?
To ask about permission we use Can ...?
Canyouwearjewellery to school?

Unit 14 79