Page 348 - Practical English Usage 3ed - Michael Swan, Oxford

may and might (2): chances etc 339
f However, certain past ideas can be expressed by may or might followed by a perfect infinitive (have + past participle).
She's late. I think she may have missed the train. Why did you do that? You might have kiUed yourself.
9 Might has a contracted negative mightn't (see 143). Mayn't is very unusual. 2 meanings
May and might are used mainly to talk about the chances of something happening, and to ask for and give permission (especially in a more formal style).
I may see you tomorrow.
Do you think I might borrow your typewriter?
Call and could are often used in similar ways to may and miglJt. For the main differences, see 345. For may and might after so that and in order llrat, see 543.
339 may and might (2): chances etc
1 chances: You may be right We may go climbing
We often use may and might to talk about the chance (possibility) that something will happen, or is happening.
We may go climbing in the Alps next summer.
Peter might phone. If he does, ask him to ring later.
I think Labour are going to win. - You may be right.
Where's Emma? - I don't know. She might be out shopping, I suppose.
May well and might well suggest stronger possibilities.
I think it's going to rain. - You may well be right - the sky's really black.
2 may and might: the difference
Might is not often used as a past form of may: both may and might are used to talk about the present or future. Might is mostly used as a less definite or more hesitant form of may, suggesting a smaller chance - it is used when people think something is possible but not very likely. Compare:
I may go to London tomorrow. (perhaps a 50% chance) Joe might come with me. (perhaps a 30% chance)
3 questions: may not used
May is not normally used to ask about the chance of something happening. Are you likely co go camping this summer? (NOT May»'6f;( gtJ et!tmfJing ...?) Has Emma gone shopping, I wonder? (NOT ,',fay Emma httlif! gtJnt!
sh6fJfJing7)
But may is possible in indirect questions (for example after Do you think). Do you think you may go camping this summer?
Might can be used in direct questions, but this is rather formal.
Might you go camping? (less natural than Do you think you may/might . .. ?)
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