1 . You haven’t gone anywhere today. You ________ your bag in the office.

A．could have left	B．must have left
C．could leave	D．must leave

2 . There was no sign of a break-in, so the thieves ________ someone on the inside helping them.

A．must have had	B．could have had
C．needn’t have had	D．might have

3 . Jack____________ his homework, for he is playing football outside.

A．couldn’t have finished	B．must finish
C．must have finished	D．might have finished

4 . —I expected him to be nervous before his speech, but he was as cool as a cucumber.
—He _______ it carefully.

A．could have prepared	B．shouldn’t have prepared
C．must have prepared	D．can’t have prepared