_____ on everyday practice, progress in English is a goal which can be achieved．
| A．Based | B．Basing | C．Having based | D．Being based |
Cook was a strict but good captain, _________ who, usually, took care of the sailors on his ship.
| A．the one | B．one | C．that | D．this |
Thanks to the application of new farming methods, the out put is now _____ it was before the year 2000．
| A．six times what | B．more than six times of |
| C．larger six times than | D．six times of that |
— The terrible accident is under investigation．
— Actually, quicker action _____ those workers trapped in the mine．
| A．might have saved | B．must have saved |
| C．should have saved | D．could have saved |
I have been living in the United States for twenty years, but seldom _____ so lonely as now．
| A．have I felt | B．I had felt | C．I have felt | D．had I felt |
In the study of modern science, there are many cases _____ soldiers can teach officers．
| A．when | B．who | C．which | D．where |