Everyone passed the exam.It _________ difficult.
| A．can’t have been | B．must have been | C．couldn’t be | D．might have been |
The three of us ________ around Europe for about a month last summer.
| A．have travelled | B．had travelled | C．travelled | D．travel |
He got up late and hurried to his office, ________ the breakfast untouched.
| A．left | B．leaving | C．to leave | D．leave |
We _________ the difficulty together, but why didn’t you tell me?
| A．should face | B．might face | C．must have faced | D．could have faced |
________ at the door before you enter my room, please.
| A．Knock | B．Knocking | C．Knocked | D．To knock |
________ with care, one tin will last for six weeks.
| A．Use | B．Using | C．Used | D．To use |