about which是一个并与从句，about是 talk about的前置。其实句子结构是：I have the book which you are talking about. 我有你谈到的那本书。从句里边有介兵短语的时候，介词要提前到先行词（which/whom等），这是一个语法。再比如：I don't like the way in which you talk to me.我不喜欢你和我说话的方式。in the way， in前置了。Mary is the lady for whom you are waiting.玛丽就是你正在等的那位女士。wait for， for前置了。就是这种用法，您明白了吗？欢迎追问。...
