Modals

1) can

Use	Examples
ability to do sth. in the present (substitute form: to be able to)	I can speak English.
permission to do sth. in the present (substitute form: to be allowed to)	Can I go to the cinema?
request	Can you wait a moment, please?
offer	I can lend you my car till tomorrow.
suggestion	Can we visit Grandma at the weekend?
possibility	It can get very hot in Arizona.

2) could

Use	Examples
ability to do sth. in the past (substitute form: to be able to)	I could speak English.
permission to do sth. in the past (substitute form: to be allowed to)	I could go to the cinema.
polite question *	Could I go to the cinema, please?
polite request *	Could you wait a moment, please?
polite offer *	I could lend you my car till tomorrow.
polite suggestion *	Could we visit Grandma at the weekend?
possibility *	It could get very hot in Montana.

3) may

Use	Examples
possibility	It may rain today.
permission to do sth. in the present (substitute form: to be allowed to)	May I go to the cinema?
polite suggestion	May I help you?

4) might

Use	Examples
possibility (less possible than may) *	It might rain today.
hesitant offer *	Might I help you?

5) must

Use	Examples
force, necessity	I must go to the supermarket today.
possibility	You must be tired.
advice, recommendation	You must see the new film with Brad Pitt.

6) must not/may not

Use	Examples
prohibition	You mustn't work on dad's computer. You may not work on dad's computer.

7) need not

Use	Examples
not necessary	I needn't go to the supermarket, we're going to the restaurant tonight.

8) ought to

Use	Examples
advice	You ought to drive carefully in bad weather.
obligation	You ought to switch off the light when you leave the room.

9) shall

instead of will in the 1st person

Use	Examples
suggestion	Shall I carry your bag?

10) should

Use	Examples
advice	You should drive carefully in bad weather.
obligation	You should switch off the light when you leave the room.

11) will

Use	Examples
wish, request, demand, order (less polite than would)	Will you please shut the door?
prediction, assumption	I think it will rain on Friday.
promise	I will stop smoking.
spontaneous decision	Can somebody drive me to the station? - I will.
habits	She's strange, she'll sit for hours without talking.

12) would

Use	Examples
wish, request (more polite than will)	Would you shut the door, please?
habits in the past	Sometimes he would bring me some flowers.

* no past forms - future forms