When asked what they would volunteer to do, said they were willing to do something they could.
A. half of these
B. half of which
C. half of whom
D. half of them
网友回答
A. half of these
B. half of which
C. half of whom
(答案→)D. half of them
解析：本题考查状语从句与定语从句的区别。由题干可知，题中when作为连词，引导时间状语从句，故逗号后缺少主句的“主语”，由此排除选项B和C。依据句意：当被问及他们自愿做什么,一半的人说他们愿意尽其所能。则选项D符合题意。