Most students like the teachers can understand them well.A. who B. when C what

问题补充：

Most students like the teachers can understand them well.

A. who B. when C, what

答案：

解析：句意：大多数学生喜欢可以理解他们的老师。先行词teachers在定语从句中作主语可以用关系代词who将其代替，所以选A。