首先看兩個句子：

She is my girlfriend who works in the hospital.

翻譯：這就是我那個在醫(yī)院工作的女朋友。

暗含：我不只有一個女朋友！這只是其中的一個！

She is my girlfriend, who works in the hospital.

翻譯：她是我的女朋友，她在醫(yī)院工作。

暗含：我只有一個女朋友！后面的定語從句起補充說明的作用！

區(qū)別：加逗號定語從句 vs 不加逗號定語從句

不加逗號定語從句（限制性定語從句）：前面的n.是一個“泛指”的籠統(tǒng)的概念！ 多選一！

加逗號的定語從句（非限制定語從句）：前面的n.是一個“具體”的明確概念！從句只是補充說明！

再各舉兩個例子感受一下什么n.是籠統(tǒng)，什么是具體：

籠統(tǒng)名詞：

There are many computer games which contain lots of violent scene that is harmful to children.

We have several methods, such as Television and Internet, to get information. These are resources which can be easily had access to.

具體名詞：

Students can develop a sense of belonging and experience team spirit, both of which may prove very important in building a career.

Harry Potter I, which is written by J.K.Rowling, is popular.

補充：“加逗號”的定語從句位于句中 vs 位于句尾

位于居中舉例：

原句：He moved to our city two years ago. He bought a new car last week.

修改：Tom, who moved to our city two years ago, bought a new car last week.

說明：定語從句位于居中，可以連接一個人的兩個動作；其中“不太重要”的動作成為中間的定從！

位于句尾舉例：

More and more people come to the ancient village during the holidays, which boosts the local economy.

說明：定語從句位于句尾，可以對前文進行“小結(jié)”，說明帶來的情況！

練習一個翻譯：漢朝是中國歷史上最重要的朝代之一，漢朝統(tǒng)治期間有很多顯著的成就。

翻譯：

The Han Dynasty, which is one of the most significant dynasties in the history of China, attained lots of remarkable achievements during the reign.