Professor Zhang handed out the textbooks to all the students except who had already taken

问题补充：

Professor Zhang handed out the textbooks to all the students,except who had already taken them.

A. these

B. ones

C. the ones

D. the others

答案：

A. these

B. ones

(答案→)C. the ones

D. the others

解析：考查代词的用法。who had already taken them是定语从句，修饰空格处的代词，由此可判断选C，the ones相当于those。