--- Do you know the reason _________ pilots turn off the plane’s lights before taking off?
---The practice is for the passengers to adjust to the dark _________ an emergency.
| A．why; for fear that | B．for which; in case of |
| C．how; for fear of | D．that; in case |
-Why didn't you remind him of the possible danger?
-But what __________？ He never listens to me.
| A．could I do |
| B．could I have done |
| C．should I do |
| D．must I have done |
-How did you like the concert last night?
-I enjoyed it very much, but the dancers __________ a better job.
| A．could have done |
| B．must have done |
| C．could do |
| D．had done |
He made good preparation for the exam. Otherwise, he __________ such rapid progress.
| A．should not have made |
| B．needn't have made |
| C．could not have made |
| D．must not have made |
You __________ the day off from work, which created a burden for everyone else.
| A．shouldn't have taken |
| B．mustn't have taken |
| C．couldn't have taken |
| D．wouldn't have taken |
We __________ the difficulty together, but why didn't you tell me?
| A．should face |
| B．might face |
| C．could have faced |
| D．must have faced |