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between "may" and "might"
I mean when I use may and when might?
Thanks
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When asking for permission, most people in the States use "may".

May I use your room?

May I go to the restroom?

May I kiss you?
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There's a tendency to use "might", "may", or "could" for logical possibility.

Rob might be waiting there now.
Rob may be waiting there now.
Rob could be waiting there now.

There's a tendency to use either "may", "can" for permission. "may" is more formal. "can" is more everyday.

Susan may go to the party if she is home by 11.
Susan can go to the party if she is home by 11.

The forms "might" and "could" are the past of "may" and "can" in reported speech:

She said Susan might go to the party.
She said Susan could go to the party.

Susan asked if she might go to the party.
Susan asked if she could go to the party.

Because of the ambiguity of sentences like "I may go to the party" (="It is possible that I will go to the party" or = "I have permission to go to the party"), I personally tend to use "might" for the logical case and "can" for the permission case. (I might go to the party. I can go to the party.) Of course, that creates an ambiguity in the case of "can" between "I have permission ..." and "I am able ...". Sometimes, you just can't win!!! On the other hand, the ambiguity with "can" seems to me a less serious one.
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Comments  
Pretty much interchangeable, Maverick, with 'might' considered slightly less probable / more hesitant / more polite than 'may' by some.

'May you have a Merry Christmas'-- in this use, only 'may' is possible.
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