There is a special group of verbs called modal verbs. These include:
can / could
will / would
shall / should
may / might
must / ought to
They are used in three main ways:
1) To show how likely something is to happen.
I will come.
I might come.
2) To show skills or abilities.
She can play the piano.
He could speak French when he was three.
3) For giving permission, orders and advice.
You must work harder.
May I leave the room, please?
Let's have a look at some examples in the questions that follow.