Hola, Inma,
In a previous reply to Remy, you gave the example:
Quizás Miguel no apruebe.
He may not pass (in the future, he hasn't done the exam yet)
Quizás Miguel no aprobara.
He may not have passed (he already did the exam and we doubt if he passed or not)
Is it possible to use the perfect here
Quizás Miguel no haya aprobado.
and if so, how would the meaning be different from the earlier two examples?
Thanks in advance for your help.