Only after he had spent several nights working on the math problem _______ to wonder whether the problem was wrongly set.
| A．that he began | B．did he begin | C．then he began | D．so that he began |
--- Is Tom still smoking?
--- No. By next Saturday he _____ for a whole month without smoking a single cigarette.
| A．will go | B．will have gone |
| C．goes | D．has been going |
In dealing with public relations, we should make every effort to prevent the _____ in personality.
| A．contact | B．contrast | C．conflict | D．connection |
I know one of the things _____I was unsure about was _____ hard it would be to climb this mountain.
| A．that; how | B．what; how | C．which; what | D．/; what |
It’s said that there are plenty of hotels in that town. There _____ be any difficulty for you to find one to stay in.
| A．mustn’t | B．oughtn’t | C．needn’t | D．shouldn’t |
Once we discover a mistake, we should not _____ it but correct it immediately, to create better conditions for economic development.
| A．ignore | B．postpone | C．deny | D．sheltered |