MODALS OF OBLIGATIONMODAL VERBS

What are MODAL VERBS?

MUST & HAVE TO

• I must finish my homework before 8

• We have to wear a uniform

They are both used to express

that something is necessary

MUST

• I must find a hotel to stay at tonight

• The speaker decides that something is necessary (INTERNAL decision)

HAVE TO

• I have to wear a uniform

• Somebody else has made the decision, it’s not the speaker’s opinion (EXTERNAL decision)

OTHER TENSES

• MUST: past & future with HAVE TO

• When I was young, we had to wear a uniform at school

• Next year you will have to study harder

MUSTN’T & DON’T HAVE TO

• Very different meanings in negative:

• You mustn’t use a dictionary

• You don’t have to use a dictionary

MUSTN’T

• You mustn’t use a dictionary.

• (It’s forbidden /prohibited)

• =can’t

DON’T HAVE TO

• You don’t have to use a dictionary. This exercise is really easy

• (It’s not necessary)

SHOULD / SHOULDN’T

• I think you should see the doctor

• I think you shouldn’t watch so much TV

• We use SHOULD/ SHOULDN’T

to give some advice