You must be tired: you have been working for hours.
He may have visited the Hermitage when he was in St Petersburg last year.
It must be a very deep lake.
That building in the distance must be the station.
You can’t have lost your passport: you must have put it into another bag.
The girl may have been frightened.
You must have left your textbook in the canteen.
They can’t give up such a brilliant idea.
You look pale: you must be tired.
This boy can’t be a good friend.