Modal Verbs

There are not many modal verbs: can, could, dare*, need*, may, might, must, shall, should, will, would. There are also modal constructions: be able to, ought to, be allowed to
They always come first in a verb formation, before other auxiliaries and the main verb:
{modal} + [auxiliary] + {main verb}
Note that modal verbs do not take a final -s for the third person singular. The verb which follows is always in the infinitive form:
He might be...
They should stay...
She could have...
We can use them with the -ing form to show continuous modality:
{modal} + {be} + {-ing}
He might be working late.
They should be coming soon.
He must be having a party.
We can use them with the past participle to show past modality:
{modal} + {have} + {past participle}
He might have been working late.
They should have seen him.
He must have gone away.
We can use be able to, be allowed to and have [got] to after modals:
{modal} + {phrase}
I will be able to...
She might not be allowed to...
They should have to...
Note that we do not use these in continuous form s.
We use mo dal verbs to show:
w hat we think or feel about a situation:
They should not have gone.
They might have been working hard.
ability to do something:
They can't speak fluently.
He could beat the record easily.
necessity:
He must stop.
They should stop.
possibility:
He could be there.
They might not win.