We have done things we ought not to have done and ________ undone things we ought to have done.
| A．left | B．leave |
| C．will leave | D．leaving |
No matter what you say, I shall________my opinion.
| A．carry out |
| B．keep up |
| C．go on |
| D．stick to |
The Panama Canal________the Atlantic________the Pacific.
| A．connects; with |
| B．joins; with |
| C．unites; with |
| D．joins; up |
All the preparations for the task________， and we're ready to start.
| A．completed |
| B．complete |
| C．had been completed |
| D．have been completed |
—I'm sorry I stepped outside for a smoke. I was very tired.
—There is no________for this while you are on duty.
| A．reason |
| B．excuse |
| C．cause |
| D．explanation |
—Would you like to go to the dinner party on Saturday?
—Thank you. I'd love to，________I'll be out of town at the weekend.
| A．because |
| B．and |
| C．so |
| D．but |