during which 和during which time 的区别

问题描述:

during which 和during which time 的区别
①They stayed with me for two weeks,____they drank all the beer I had.
A.for which B.which time C.during which time D.during which
选 C

C
这里是说在……那段时间内,当然要有time.
后面的句子不缺成分,所以这里的引导词不能是that / which,因为这两者是要充当成分的.
没有during which这种用法.