They ...........(must / can't ) have heard some bad news, they looked very shcoked.
Must
You ................ (have to / can't) be telling the truth, I don't believe a word of what you are saying
Can't
I think it's likely that the film will be a success. The film................. a success. (might)
might be
It's not possible that my friends have seen this film. My friends............ this film. (can't)
Can't have seen
It's possible that my brother has bought a new phone. My brother.......................... a new phone. (could/ buy)
could have bought
I'm certain that the girl on the sofa is wearing my jacket. The girl on the sofa............ my jacket. (must)
Must be
I'm convinced that your brother has forgotten my birthday. Your brother ................... my birthday. (must)
must have forgotten
She ................. (can't/ must ) be our teacher, she is only 19.
Can't