She might not have laughed at the joke because...
she didn't understand it
She must have been happy because...
she won some money!
She couldn't have gotten lost because...
she had a map
They must have passed the exam because...
they studied a lot
Someone called but I don't know who it was. It (must / may ) have been Alice.
may
I am not in touch with my high school friend Lola any more. She might have gotten married or she (might / must) have moved away.
might
Irv looks unhappy. Maybe he lost his job or his girlfriend (must / might) have broken up with him. I don't know.
might
I told Charles - only Charles - my secret and now everyone knows! He (must / might) have told everyone.
must
