I don’t know the man is looking after the old woman.A. thatB. whatC. whichD. /

问题补充：

I don’t know the man is looking after the old woman.

A. that

B. what

C. which

D. /

答案：

(答案→)A. that

B. what

C. which

D. /

解析：根据先行词the man可知选A,than在定语从句中既可以指人也可以指物.