ПОМОГИТЕ ПОЖАЛУЙСТА С АНГЛИЙСКИМ!!!Fill the gaps using must, may или cant.It

ПОМОГИТЕ ПОЖАЛУЙСТА С АНГЛИЙСКИМ!!!

Fill the gaps using must, may либо cant.

It _____ be true. I dont believe you!
Mike _______ be at the university right now. I saw him 10 minutes ago.
John _______ be a teacher. I dont really know.
This _______ be my towel. I cant recognize it.
She ______ be playing the piano now. I can hear music.
This milk _______ go off if you dont put it into the fridge.
She _______ have been at the meeting when I called her.
They _______ left for London last week, they didnt tell me.
She _______ have been running very fast. She was totally out of breath.
Helen has no friends. She _______ be very lonely.