______ it have been the failure to pick up directions from the ground control that caused the air crash?
| A．Must | B．Could | C．Would | D．Should |
To improve the quality of our products, we asked for suggestions __________ had used the products.
| A．whoever |
| B．who |
| C．whichever |
| D．which |
—How about camping this weekend, just for a change?
—OK,__________ you want.
| A．whichever |
| B．however |
| C．whatever |
| D．whoever |
At the meeting place of the Yangtze River and the Jialing River __________, one of the ten largest cities in China.
| A．lies Chongqing |
| B．Chongqing lies |
| C．does lie Chongqing |
| D．does Chongqing lie |
The moment I saw her, I __________ her, although she changed a lot through years.
| A．knew |
| B．realized |
| C．noticed |
| D．recognised |
Alexander tried to get his work __________ in the medical circles.
| A．to recognize |
| B．recognizing |
| C．recognize |
| D．recognized |