His parents were teachers in that school, lost their lives in order to save
their students in the earthquake.
A. none of them
B. both of them
C. none of whom
D. both of whom
网友回答
A. none of them
B. both of them
C. none of whom
(答案→)D. both of whom
解析：经过分析，可知这个句子中包含一个非限制性定语从句。Them不能引导定语从句，又因为His parents是两个人，表示两者故用both。