This document discusses modals used to make guesses about the present. Must is used to express certainty or high probability, such as deducing that A must be bigger than C if A is bigger than B and B is bigger than C. Can't expresses that something is untrue or nearly impossible, like saying it can't be the postman at the door so early. May, might, and could express varying degrees of possibility, with could implying a higher probability than might, which implies something is possible but not very likely, and may implying a moderate probability.

1. MODALS OF DEDUCTION
AND SPECULATION

2. TO MAKE GUESSES ABOUT THE PRESENT
● must
● can’t
● may +
infinitive
● might
● could

3. MUST
● We use it to express that something is
certain or highly probable.
If A is bigger than B, and B is bigger than C…
… then A must be bigger than C.
Mary keeps crying – she must have a problem.

4. CAN’T, COULDN’T
● We use can’t to express that something is
not true or nearly impossible.
It can’t be the postman at the door. It’s only
seven o’clock.
● We use couldn’t to express that something
is impossible.
She couldn’t be working. She is on maternity
leave!

5. MAY, MIGHT, COULD
● We use them when there is a possibility of it
happening.
He could be working (Perhaps a 70% chance)
I may go to Edinburgh tomorrow (Perhaps a
50% chance)
Peter might come with me (Perhaps a 30%
chance. It is possible but not very likely to
happen)