impressed me most about the woman was that she looked after the old man for twenty years without any plaint.
A. That
B. Which
C. What
D. As
网友回答
A. That
B. Which
(答案→)C. What
D. As
解析：词义辨析。A. 那个 B.哪一个 C. 什么 D. 由于；句意：关于这个女人给我们印象最深的是她毫无怨言的照顾了这位老人二十年。主语从句缺少主语，故选C。