. I have taught hundreds of students having been working in their fields for years.A. som

问题补充：

. I have taught hundreds of students, having been working in their fields for years.

A. some of whom

B. some of them

C. most of whom

D. who

答案：

(答案→)A. some of whom

B. some of them

C. most of whom

D. who

解析：考查定语从句。句中先行词为students，在从句中作some of的宾语，故用关系词whom。句意：我已经教过几百位学生，其中一些已经在他们领域工作多年了。