Modal verbsofobligation

mustor

have to

mustor

have to

modal

mustor

have to

indicative ‘helping verb’

be careful with+ive—ive?ive

be careful with+ive—ive?ive

in both form and meaning

form

I must go.

I have to go.

+ive

He must go.

He has to go.

+ive

You mustn’t go.

I don’t have to go.

—ive

Must she go?

Does she have to go?

?ive

-

She had to go.

past

meaning

+ive

I must wash my hair.

You must arrive early.

must [+ive] expressesstrong personal

obligation

personal obligation means:- dictated by people- imposed by a 1st or 2nd person- what the speaker or listener wants

Must is also used in formal regulations and warnings

Bookings must be made at least seven days before departure.

I have to get up early tomorrow.

Policemen have to weara uniform.

In tennis, you have to hit the ball over the net.

have to [+ive] expressesstrong impersonal

obligation

impersonal obligation means:- dictated by circumstance- dictated by a 3rd person- other people’s wishes - laws- rules

—ive

You mustn’t smoke in here.

You mustn’t tell anyone.

must [—ive] expressesstrong negative obligation

or prohibition

We don’t have to get up earlyat weekends.

You don’t have to tell your parents if you don’t want.

have to [—ive] expressesabsence of obligation

have to [—ive] expressesabsence of obligation—there’s no need—

we can expressthe same concept

(with different emphasis)using ‘can’

We don’t have to get up earlyat weekends.

We can get up earlyif we want.

?ive

Must I eat the vegetables?

must [?ive] is rarebetween adults

must [?ive] is used when children talk to

figures of authority(parents, school teachers, etc)

with the meaning:“is it really necessary for me

to do this thing?”

you can ignoremust [?ive]

Do I have to do my homework for next Monday?

Do they have to book the exam?

have to [?ive] is used for (almost) all questions about

obligations

past

I must go to the dentistnext week.

I had to go to the dentistlast week.

I must go to the dentistnext week.

I had to go to the dentistlast week.

+ive —ive ?ive

must

personal obligationI must wash my hair

negative obligationYou mustn’t tell anyone.

notused-

have to

impersonal obligationI have to go to the dentist.

absence of obligationWe don’t have to get up early.

allquestionsDo I have to do it for Monday?

Practice1 must go to bed2 must find out 3 don’t have to answer4 has to vote5 must throw out6 mustn’t hit your opponent7 must come round8 have to get

9 have to take off 10 must turn down 11 have to pay taxes12 don’t have to go to work

taken from Oxford English Grammar Course byMichael Swan & Catherine Walter

http://oald8.oxfordlearnersdictionaries.com/dictionary/have-to

http://www.englishgrammarsecrets.com/musthaveto/menu.php

www.davidnicholson.it

adapted by V. Pardo