1.This is the pencil whose point is broken.
这就是那个折了尖的铅笔.
(whose 指物,在限定性定语从句中作定语)
2.He came back for the book which he had forgotten.他回来取他丢下的书.
（which指物,在限定性定语从句中作宾语,可以省略）
3.关系代词which的先行词可以是一个句子,例如：
He said he saw me there,which was a lie.
他说在那儿看到了我,纯属谎言