It has come to my notice some of you have missed classes.A. whatB. whichC. thatD. when

问题补充：

It has come to my notice some of you have missed classes.

A. what

B. which

C. that

D. when

答案：

A. what

B. which

(答案→)C. that

D. when

解析：考查定语从句。从句不缺少句子成分，it指的是后面从句内容，故引导词用 that。选C。