Ch 4
Modals of Deduction
She must be tired · It might be Tom · That can't be right
We use modals to guess about the present from what we see or know.
He's yawning. He must be tired.
I'm almost sure it's true.
She isn't answering. She might be asleep.
It's possible.
That can't be Ana — she's in Paris.
I'm almost sure it isn't true.
about 50%
might · may · could
The opposite of must is can't, not mustn't.
must / might / may / could / can't + infinitive
You must know her — you went to the same school.
It could be in your other bag.
No to: must be, not must to be.
must / might / can't + be + -ing
The lights are on. They must be watching TV.
He can't be working — it's Sunday.
She might not be at home.
Maybe she isn't.
She can't be at home — her car isn't there.
I'm almost sure she isn't.
He mustn't be hungry — he just ate.
→
He can't be hungry — he just ate.
negative deduction → can't
She must to be at work.
→
She must be at work.
no to after a modal
It can be Tom at the door.
→
It could / might be Tom at the door.
possibility about now → could / might
They must watch a film — it's noisy.
→
They must be watching a film.
happening now → be + -ing
Look around you and make deductions.
1
Someone is knocking at the door. Who could it be?
2
Your friend isn't replying to messages. Why?
3
Look at a person near you. What must they be thinking?
4
Say something that can't be true about your teacher.
Recap
almost sure: yes
must + infinitive
He must be tired.
possible
might / may / could
It might be Tom.
almost sure: no
can't + infinitive
That can't be right.
now, in progress
must be + -ing
They must be sleeping.
maybe not
might not
She might not know.