想知道in which在此处的应该如何理解?

题目

想知道in which在此处的应该如何理解?
在背新概念3 是第5课最后一段中 he hand at last been allowed to send a fax in which he informed the editor that he had been arrested.
我真不理解在此处in which in which 除了 where的意思外 还有别的用法吗?
打错了 hand 换成have

答案

此处的in which 等于that .是解释fax的内容的.就是这个传真的内容是什么.可以简单理解为 “在.里”,在传真里,他通知编辑他被捕了.
in which一般不用做where,倒是常常替换that.