Page 360 - Practical English Usage 3ed - Michael Swan, Oxford

Ifyou will come this way ... I'll pay for the drinks.
people.
I'll definitely work harder next term.
e permission: can, could, may, might You can use the car ifyou like. Could I talk to you for a minute? May we use the phone?
She will keep interrupting Shall I give you a hand?
modal auxiliary verbs: meanings 354
b prohibition: must not, may not, cannot Students must not use the staffcpr park. Books may not be taken out ofthe library. You can't come in here.
c weak obligation; recommendation: should, ought to, might, shall (in questions)
You should try to work harder. You might see what John thinks. She really ought to wash her hair. What shall we do?
d willingness, volunteering, resolving, insisting and offering: will, shall (in questions)
Do you think I might take a break now?
f absence of obligation: needn't
You needn't work this Saturday.
9 ability: can, could
She can speak six languages.
Anybody who wants to can join the club.
These roses can grow anywhere.
When I was a baby I could put my foot in my mouth. You could get to my old school by bus, but not by train.
4 speaker's and hearer's point of view
Obligation, permission etc are usually seen from the speaker's point of view in statements and the hearer's in questions. Compare:
- You must go and see Ann. (I think it is necessary.)
Must you go and see Ann? (Do you think it is necessary?)
- You can borrow my car. (I give permission.)
Can I borrow your car? (Will you give permission?)
5 forms in indirect speech, after if etc
Instead of can, will, shall and may, we use could, would, should and might to express the same meanings in past indirect speech, (see 275), in some sentences after if (see 258), and in 'future in the past' sentences (see 221).
I knew it couldn't be John.
I told you you wouldn't be ready in time.
Ifyou stopped criticising, I might get some work done.
I should be grateful ifyou would let me know your decision as soon
as possible.
They knelt in front of the child who would one day rule all England.
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