( ) 14. The students handed in their test papers to the teacher _______ .
| A．one after the others | B．one by one |
| C．one after one | D．one after the other |
―Was the doctor there when you arrived?
―Yes, but he ______ out a moment later.
| A．had gone | B．has gone |
| C．went | D．is going |
―Why? Where is the key to the sound lab?
―Dear me! You _______ it in the taxi！
| A．have never left | B．never left |
| C．haven’t left | D．didn’t leave |
―________ for Beijing?
―Yes. And I’ll come back in three months.
| A．Have you left | B．Are you leaving |
| C．Do you leave | D．Did you leave |
―What were you doing when I called you yesterday afternoon?
―I ________ my homework and I was starting to take a bath.
| A．had just finished | B．was finished |
| C．have already finished | D．was going to finish |
―Twenty dollars, please!
― How terrible!―I ________ to bring my wallet with me.
| A．was forgetting | B．forgot |
| C．had forgotten | D．am forgetting |