The past 30 years has ______ the great changes that have taken place in China.
| A．seen | B．noticed | C．watched | D．looked |
The research is so designed that, once _______, nothing can be done to change it.
| A．begins | B．having begun | C．begun | D．Beginning |
The most important thing _______ we should pay attention to is the first thing ________ I have said.
| A．which; that | B．that; which | C．that; that | D．which; which |
_____, the great mother, in order to save her sick child, kept waiting for four hours in the heavy snow.
| A．It depends | B．Take it easy | C．Believe it or not | D．It is OK |
Was it in 2002 __________ he was still at middle school __________ the boy became expert at computer?
| A．that; where | B．when; where | C．that; when | D．when; that |
You can’t imagine what difficulty we had home in the snowstorm.
| A．walk | B．walked | C．to walk | D．walking |