非限定定语从句「经典非限制性定语从句」

非限定性定语从句的使用有以下四种情况：

①当关系代词指代整个主句内容时

当关系代词指代整个主句内容时，用非限制性定语从句。

The boy was away from home for a week, which worried his parents very much.

The fire lasted for a whole night, which caused great damage.

The book is very interesting, as most readers say.

②当先行词指的是世界上独一无二的事物或专有名词时。

当先行词指的是世界上独一无二的事物或专有名词时，用非限制性定语从句。

Jinan, which is a nice city, attracts many visitors every year.

The sun, which gives off a great deal of heat, is a great source of energy.

Charles Smith, who was my former teacher, retired last year.

③先行词指的是某人只有的一个亲属

先行词指的是某人只有的一个亲属（son, daughter, father, mother, wife等）时，用非限制性定语从句。

I have an elder brother, who works in Beijing.

I have an elder brother who works in Beijing.

这两句话的意思是有区别的，前一句是说只有唯一的一个哥哥，后一句是说可能不只是一个哥哥。

Her daughter, who is now studying in New York, graduated from our school.

My father, who is a teacher, is very strict with us.

④在some/many/few/a few/little/much/most/half + of + which/whom 等结构时

出现some/many/few/a few/little/much/most/half + of + which/whom 等结构时，常用非限定性定语从句。

I earn only 1,000 dollars a month, half of which is spent on my car.

There’s too much information on the Internet, some of which is unreliable.

I have invited more than one hundred friends to the party, most of whom are from abroad.