Lesson 1 - Grammar - FILM AND THEATRE - Page2
What if all that happened yesterday? Your neighbour told you someone knocked on your door when you were not home. And you start wondering who it was.
Again if you’re almost sure it was Jessica, you’d say:
It must have been Jessica.
If you’re sure it wasn’t her because she was with you then, you’d say:
It can’t have been Jessica.
If you don’t know who it was and it’s possible that it was Jessica, you’d say:
It may have been Jessica.
It could have been Jessica.
It might have been Jessica.
You may also speculate about what people were doing in the past and then you use the continuous forms.
I didn’t hear the phone. I must have been sleeping in the garden.
She can’t have been doing housework when I called. She sounded sleepy.
She may/might/could have been doing her homework when I knocked on her door but she may have been playing computer games, too.