در مورد تفاوت بین استفاده از may have pp و might have pp بحثهای فوق العاده زیادی وجود داره که هنوزم خود انگلیسی زبانها سر این موضوع اختلاف نظر دارن. اما توضیحی که من بیشتر دیدم این بوده که :
اگر I might have been failed the test باشه، یعنی
احتمال اینکه اون امتحانرو بیفتم وجود داشت (الان میدونیم که قبول شدی)
اگر I may have been failed the test باشه، یعنی
ممکنه اون امتحان رو افتاده باشم. هنوز معلوم نیست قبول شدی یا نه. و احتمال میدی که شاید امتحان رو افتاده باشی.
چند تا مثال:
Fifty years ago he might have been dismissed for being ill but as his uncle owned the factory, he wasn't. - (i) he might have been, That's the sort of world he lived in.
Fifty years ago he may have been dismissed for being ill. - it is a possibility that he was dismissed; we don't know.
A: "The great explorer's life was not well documented. For instance, there is no record of him between 1898 and 1900 and many think that, during those years, hemay have gone to Arabia."
.........
Real Madrid may have taken an early lead" implies that we don't know whether Real Madrid took an early lead but we think it is a possibility. In fact, we know that Real Madrid did not take an early lead here, so "may" is not possible for me.
......
She might have been badly hurt (if she had not been lucky, if circumstances had been otherwise). Here mightis obligatory and may not possible, but this is just a consequence of the rules for unreal conditional sentences.
- A worker may have been dismissed fifty years ago. We just don't know if they were.
.....
"may" means something is possible. It does not mean something would be possible. "Might" means either that something was possible or that something would be possible.