非限制性定语从句which可以指代前面整个句子,也可以指代某一成分
My house,which I bought last year,has a lovely garden.
我去年买的那套房子有一个漂亮的花园.(先行词 my house )
The weather turned out to be very good,which was more than I had expected.
天气变好了,这出乎我的意料.（将整个主句作为先行词）通过上下文一般不会