把定语从句连同引导词一起拿出来,把引导词去掉,看这个句子是不是缺少主语?宾语?表语?,如果不缺少,就是完整了.
如：
This is the book that I bought yesterday.
that I bought yesterday
去掉that:I bought yesterday（少了宾语）
The house is where I used to live.
where I used to live
去掉where:I used to live句子完整.
不管是什么从句,它必须有被修饰的主体,从句本身是主谓宾存在的!而且主句和从句的时态须一致.
