MODALS OF DEDUCTION MUST, CAN´T, MIGHT/MAY/COULD

MODALS OF DEDUCTION:MUST, CAN´T, MIGHT/MAY/COULD
FORM
Subject+modal+base form
FUNCTION
can´t
we use can´t to say that its impossible that something is true
must
we use must to say that we are sure that something is true
might/could/may
we use might/could/may to say that something is possibily true
EXAMPLES
MUST

• He must live near here because he comes to work on foot. We don’t know where he lives but we’re sure it’s not far away.
• Come inside and get warm – you must be freezing out there.
• You’re a zookeeper? That must be very interesting.
• 

MIGHT

• Did you hear that? I think there might be a burglar downstairs. She’s not sure there’s a burglar but she thinks it’s possible.
• We’ll try to get there early but we may arrive late if there’s a lot of traffic.
• Don’t put it up there. It could fall off and hit someone.

Might, may and could are also followed by an infinitive without ‘to’.

CAN´T

• It can’t be a burglar. All the doors and windows are locked. He doesn’t know it’s not a burglar but he feels sure it’s not.
• It can’t be far away now. We’ve been driving for hours. Where’s the map?
• Really? He has to work on Christmas Day? He can’t feel very happy about that.

Like the other verbs, can’t is followed by an infinitive without ‘to’.

Remember that all of these modal verbs – must, might, may, could and can’t have other uses. These are covered in another section.

TAG QUESTIONS

FUNCTION

We use tag questions to check information we are not sure about or to confirm information that we are almost certain about.

FORM

Affirmative main verb, negative tag question

main verb be 

you´re Claudia, aren´t you?

simple tenses

Rob likes Italian food, doesn´t he?

Modals

Julie should call more often, shouldn´t she?

Present perfect 

you´ve just told him, haven´t you?

past progessive

he was taxting his ex-girlfriend again, wasn´t he?

Negative main verb, affirmative tag question

Pedro and araceli aren´t studying in the U.S are they?