---I’m sorry. I _________ at you the other day.
---Forget it. It was a bit out of control myself.
| A．shouldn’t shout | B．shouldn’t have shouted |
| C．mustn’t shout | D．mustn’t have shouted |
——Is there any possible way to help them get rid of such a bad habit?
——To tell the truth, it’s very hard. But we_______ on this problem.
| A．worked | B．had worked | C．are working | D．had been working |
Help others whenever you can _______ you will earn respect from others without difficulty.
| A．and | B．or | C．unless | D．but |
The Internet celebrated its birthday on September 2nd, by which time 40 years _______ since the first successful transfer of data between two computers.
| A．has passed | B．had passed | C．passed | D．have passed |
—— I haven’t seen Johnson these days.
—— I think she _______ a conference in Beijing, but I’m not sure.
| A．should be attending | B．might be attending |
| C．could have attended | D．must have attended |
The use of Chinese by teachers in ______ English classroom must be restricted because it will decrease _______ time when students are exposed to the English language.
| A．the; / | B．an; / | C．/; the | D．an; the |