当先行词是专有名词或物主代词和指示代词所修饰时，其后的定语从句通常是非限制性的。
例如：
Charles Smith， who was my former teacher， retired last year. 查理·史密斯去年退休了，他曾经是我的老师。
My house， which I bought last year， has got a lovely garden. 我去年买的的那幢房子带着个漂亮的花园。
This novel， which I have read three times， is very touching. 这本小说很动人，我已经读了三遍。
非限制性定语从句还能将整个主句作为先行词， 对其进行修饰， 这时从句谓语动词要用第三人称单数
例如：
He seems not to have grasped what I meant， which greatly upsets me. 他似乎没抓住我的意思，这使我心烦。
Liquid water changes to vapor， which is called evaporation. 液态水变为蒸汽，这就叫做蒸发。
