问题补充:
Only at that time how much time she had wasted.
A. Mary did know
B. did Mary know
C. does Mary know
D. Mary does know
答案:
A. Mary did know
(答案→)B. did Mary know
C. does Mary know
D. Mary does know
解析:考查倒装句。Only 放在句首后接状语时,后面使用部分倒装的形式。句意:只有在那时玛丽才知道她已经浪费了多少时间。