_____ what he can do. He might get a job tomorrow. He might stay out of work for weeks.
| A．We didn’t know | B．He doesn’t know |
| C．There is no knowing | D．It was known that |
_______ what would happen, none of them could find a way out.
| A．Left wondering | B．Having left wondering |
| C．Leaving to wonder | D．Having left to wonder |
—— Where did Mary’s parents buy the beautiful vase?
—— It was in the same village _______ they spent their holidays last year.
| A．that | B．when | C．as | D．where |
——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 |