He paid for a seat, when he ______ have entered free.
| A．could | B．would | C．must | D．need |
He called the police for help, that the problem was more than he could deal with.
| A．having been realized | B．realizing | C．realized | D．had realized |
Most of the students have hardly ever been to the Grand Canyon, __?
| A．haven’t they | B．have they | C．aren’t they | D．are they |
We had an anxious couple of weeks ______ for the results of the experiment.
| A．wait | B．to be waiting | C．waited | D．waiting |
I don’t think English is a language as Russian.
| A．more difficult | B．as difficult as | C．such difficult | D．as difficult |
—I’m sorry. I ______ at you the other day.
—Forget it. I 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 |