选择during the Olympic Games many people served as volunteers,( )were young colleg
问题描述：
选择during the Olympic Games many people served as volunteers,( )were young colleg
during the Olympic Games many people served as volunteers,( ) were young college students.
most of them?
most of which?
most of whom?
most of what?
答
B,非限制性定语从句,which指代前面提到的volunteers