Modals - English Grammar
1) can
UseExamples
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
UseExamples
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
UseExamples
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
UseExamples
possibility (less possible than may) * It might rain today.
hesitant offer * Might I help you?

5) must
UseExamples
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
UseExamples
prohibition You mustn't work on dad's computer.
You may not work on dad's computer.

7) need not
UseExamples
not necessary I needn't go to the supermarket, we're going to the restaurant tonight.

8) ought to
UseExamples
advice You ought to drive carefully in bad weather.
obligation You ought to switch off the light when you leave the room.

9) shallinstead of will in the 1st person

UseExamples
suggestion Shall I carry your bag?

10) should
UseExamples
advice You should drive carefully in bad weather.
obligation You should switch off the light when you leave the room.

11) will
UseExamples
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

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