(1) in which (2) on which （3） at which （4）by which (5) with which (6)about which 分别
问题描述：
(1) in which (2) on which （3） at which （4）by which (5) with which (6)about which 分别
(1) in which (2) on which （3） at which （4）by which (5) with which (6)about which
（7）from whom 怎样使用 急
答
你看他们都是定语从句先行词吧,所以which前面的介词其实都是后面从句的介词提前的.
你先把从句中缺什么成分找出来,把which所代表的主句中的词带到从句中的缺空处,你就可以根据语义理解需要什么介词使从句完整,你根本不需要知道他们跟which放在一起是什么意思.比如by：可以表示时间,方式,被动什么的