MODAL VERBS
OBLIGATION must
have to
need to
You must do your homework every night
We have to check everyone's ID
She needs to go to the doctor. She gets headaches every day.
PROHIBITION can’t
mustn’t
He mustn't / can’t eat peanuts. He's allergic to nuts
NO OBLIGATION don’t have to
needn’t
You don't have to / needn’t pay now. You can pay later
ABILITY can
could
be able to
managed to
I can play the piano.
I could read when I was four.
When the computer crashed yesterday, I was able to fix it
The burglar managed to get in through the bathroom window.
PERMISSION can /could /may /
might
be allowed to
Can I take this chair, please?
May I leave early? Could I leave early?
Although I was underage, I was allowed to enter the race.
When I was a child, I could do basically anything that I wanted to do.
POSSIBILITY may / may not
might / might not
could
Where are my keys? They may / might / could be in the car.
We may not / might not go to the party
DEDUCTION can’t
must
Everyone is wearing a jacket. It must be cold.
ADVICE should
ought to
had better
You shouldn't smoke. It's bad for your health.
You ought to study
You’d better study
MODAL PERFECT
formed by a modal + have + Past Participle
e.g. He can’t have understood the lesson because he
wasn’t listening.
(it is not possible that he understood the lesson)
must have been logical deduction in the past The lights are off. They
can’t have been impossibility in the past
(impossible deduction)
They had a lot of work to do and li
can’t have finished
might
may have been
could
possibility in the past
(possible deduction)
My grandfather
when he was a young man, but I'm
could have been suggest an alternative past action, even though it
is to late
We could have bought
decided to use the money to go on
should / ought to have been criticism or regret after an event We should / ought to have left
are going to be late
shouldn’t / have been criticism or regret after an event I shouldn’t have eaten
