Where's Peter?    He may be at school  (= perhaps he is at school)

                     He might be in class (= perhaps he is in class)


 He may be wrong / He might be wrong


The negative forms are may not and might not (mightn't).

He may not be wrong (=perhaps he is not wrong)

It might not be true (=perhaps it is not true)


Sometimes COULD  has a similar meaning to "may" and "might".

  The phone is ringing. It may/might/could be Tim


Study this example:




But couldn't  is different from "may not" and "might not". Compare:

It may/might not be true (perhaps it is not true)

It couldn't be true ( it is not possible that it was true)


I don't know where to go on holiday this summer. I may/might go to Malta ( perhaps I will go to Malta)

Tim might not / may not come to the exam tomorrow ( perhaps he will not come )