May (have) and might (have)

We use may or might to say that something is possible. You can say.

• He may be in his office.  or   He might be in his office.

The negative is may not and might not

• Jack might not be in his office. (= perhaps he isn't in his office)
• I'm not sure whether I can lend you any money. I may not have enough. (= perhaps I don't have enough)

Study the structure

I/you/he (etc.) {may} (not)     { be in his office                       {might} (not)   { be having/waiting, etc.                                                   know/have/do, etc.

To say what was possible in the past, we use may have (done) and might have (done)

• A: I wonder why Ann didn't answer the doorbell.
• B: Well, I suppose she may have been asleep. ( = perhaps she was asleep)
• A: Why didn't he say hello when he passed us on the street?
• B: He might have been daydreaming. ( = perhaps he was daydreaming)
• A: I can't find my bag anywhere.
• B: You might have left it in the store. ( = perhaps you left it)
• A: I wonder why Jill didn't come to the meeting.
• B: She might not have known about it. ( = perhaps she didn't know)

Study the structure

I/you/he (etc.) {may}       (not)  have { been asleep                       {might}     (not)  have { been daydreaming/waiting, etc.                                                               known/left/had, etc.

You can use could instead of may or might. But with could the possibility is smaller.

• "Where's Jack?" "I'm not sure. He could be in his office, I suppose, but he's not usually there at this time."