1) 定语从句有限制性和非限制性两种。限制性定语从句是先行词不可缺少的部分,去掉它主句意思往往不明确;非限制性定语从句是先行词的附加说明,去掉了也不会影响主句的意思,它与主句之间通常用逗号分开,例如: This is the house which we bought last month.这是我们上个月买的那幢房子。(限制性)
The house, which we bought last month, is very nice.这幢房子很漂亮,是我们上个月买的。(非限制性)
2) 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。
练习:下面的选项哪个是正确的? Argentina is no longer the place___________ once considered itself the world's grainfield.
a. what b. that c. which d. one
答案:C is the answer as it is a non-defining reative clause. (Therefore, we can not use 'that'.)