can/could/may/might [compare > 11.34, 11.36-38]:
Can I stay out late? you (etc.) can/can't/mustn't stay out late
Could I stay out late?
May I stay out late? you (etc.)may/may not/mayn't/mustn't stay out late Might I stay out late?
can/could (= be free to) present or future reference:
/ can see him now/tomorrow
I could see him now/tomorrow
Verbs and verb phrases related in meaning to can/could/may/might/mustn't
(not) be allowed to. You're (not) allowed to stay out late
(not) be permitted to. You're (not) permitted to stay out late
be forbidden to: You're forbidden to stay out late
be prohibited. Smoking is (strictly) prohibited
be not to: You 're not to smoke
negative imperative: Don't smoke1
11 Modal auxiliaries and related verbs
11.20 Asking for permission/responding: 'can/could/may/might'
Requests for permission can be graded on a 'hesitancy scale’, ranging from a blunt request to an extremely hesitant one. Requests for permission can refer to the present or future. The basic forms are:
Can
Could I borrow your umbrella (please)'?
May
Might
1 Can is the commonest and most informal:
Can I borrow your umbrella (please)?
A few (old-fashioned) native speakers still hold that can is the equivalent of am/is/are able to and therefore may must be used instead. The idea of e.g. asking for a favour is less strong in can than in could/may/might.
2 Could is more 'hesitant' and polite than can. We often use it when we are not sure permission will be granted: Could I borrow your umbrella (please)?
3 May is more formal, polite and 'respectful' than can and could: May I borrow your umbrella (please)?
4 Might is the most hesitant, polite and 'respectful' and is rather less common than the other three: Might I borrow your umbrella (please)?
In practice, can, could and may are often interchangeable in 'neutral' requests.
Common responses with modals are: e.g.
- affirmative: Of course you can/may. (Not "could*/'might")
- negative: No, you can't/may not. (Not "could not"/"might not")
Numerous non-modal responses are possible ranging from the polite Of course (affirmative), I'm afraid not, I'd rather you didn't (negative), to blunt refusal like Certainly not. A polite refusal is usually accompanied by some kind of explanation (I'm afraid you can't because.).
Permission to ask an indiscreet question may be requested with the formulas if I may ask and (more tentative) if I might ask: How much did you pay for this house if I may/might ask?
11.21 Asking for permission with 'can't' and 'couldn't'
Can't and couldn't are often used in place of can and could when we are pressing for an affirmative answer [> 13.6]:
can't I stay out till midnight (please)?
Couldn't
May I not? is old-fashioned.
Mayn't I? is unlikely.
Might I not.? is rare, but all these forms occur in formal style.
Modals, etc to express permission/prohibition
11.22 Very polite requests: 'can/could/may/might'
There are numerous variations on straightforward request forms to express degrees of politeness. Possibly is commonly added to make requests more polite. Requests may be hesitant:
Can/Could I (possibly)
Do you think I could/might use your phone?