表语从句的定义表语从句就是用一个句子作为表语.可是.这句话：This is the house where I live

This is the house where I lived before。肯定不是表语从句。就如你的理解,是定语从句在修饰表语house。很多参考书都有写纰漏或错误之处嘛。表语从句就是用一个句子作为表语。如：This is what I said yesterday。(what I said yesterday作表语。）What you need is just what I need。(What you need是主语从句,what I need是表语从句。）The fact is that she loves me。The problem is whethar it will rain tomorrow。小幽ice提供的例句也是。表语从句由that(可省）,if/whether,或wh-引导。