非限制性定語從句句型，一起來看看吧。
1) 定語從句有限制性和非限制性兩種，限制性和非限制性定語從句。限制性定語從句是先行詞不可缺少的部分，去掉它主句意思往往不明確；非限制性定語從句是先行詞的附加說明，去掉了也不會影響主句的意思，它與主句之間通常用逗號分開，例如：
This is the house which we bought last month. 這是我們上個月買的那幢房子。（限制性）
The house, which we bought last month, is very nice.這幢房子很漂亮，是我們上個月買的。（非限制性）
2) 當先行詞是專有名詞或物主代詞和指示代詞所修飾時，其後的定語從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，他曾經是我的老師。
My house, which I bought last year, has got a lovely garden. 我去年買的的那幢房子帶著個漂亮的花園，英語語法《限制性和非限制性定語從句》。
This novel, which I have read three times, is very touching. 這本小說很動人，我已經讀了三遍。
3) 非限制性定語從句還能將整個主句作為先行詞, 對其進行修飾, 這時從句謂語動詞要用第三人稱單數，例如：
He seems not to have grasped what I meant, which greatly upsets me. 他似乎沒抓住我的意思，這使我心煩。
Liquid water changes to vapor, which is called evaporation. 液態水變為蒸汽，這就叫做蒸發。
說明：關係代詞that和關係副詞why不能引導非限制性定語從句。
限制性和非限制性定語從句
1) 定語從句有限制性和非限制性兩種。限制性定語從句是先行詞不可缺少的部分，去掉它主句意思往往不明確；非限制性定語從句是先行詞的附加說明，去掉了也不會影響主句的意思，它與主句之間通常用逗號分開，例如：
This is the house which we bought last month.這是我們上個月買的那幢房子。（限制性）
The house, which we bought last month, is very nice.這幢房子很漂亮，是我們上個月買的。（非限制性）
2) 當先行詞是專有名詞或物主代詞和指示代詞所修飾時，其後的定語從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，他曾經是我的老師。
My house, which I bought last year, has got a lovely garden. 我去年買的.的那幢房子帶著個漂亮的花園。
This novel, which I have read three times, is very touching. 這本小說很動人，我已經讀了三遍。
3) 非限制性定語從句還能將整個主句作為先行詞, 對其進行修飾, 這時從句謂語動詞要用第三人稱單數，例如：
He seems not to have grasped what I meant, which greatly upsets me. 他似乎沒抓住我的意思，這使我心煩。
Liquid water changes to vapor, which is called evaporation. 液態水變為蒸汽，這就叫做蒸發。
說明：關係代詞that和關係副詞why不能引導非限制性定語從句。
附：非限制性定語從句1. Everyone in our class was working hard and doing what we could _______ a good college.
A. enter B. to enter
C. entering D. entered
【陷阱】容易誤選A。有的同學一看到空格前的情態動詞 could 就斷定此處應填動詞原形 enter。
【分析】其實正確答案應是B。此句為省略句，即在 could 後省略了動詞 do，若把句子補完整應為Everyone in our class was working hard and doing what we could do to enter a good college。即句中的不定式短語(to enter a good college)是用作目的狀語的，而不是與情態動詞(could)一起構成謂語。請再看類似例句：
(1) They did what they could to comfort her. 他們儘量安慰她。
(2) They did everything they could to save her life. 他們盡一切力量拯救她的性命。
(3) He studies as hard as he could to catch up with his classmates. 他拼命學習以便趕上他的同學。
值得指出的是，這也並不是說今後只要遇到類似結構的題就一定選帶to不定式。請看以下試題：
(4) He ran as fast as he could _____ to catch the early bus.
A. to hope B. hope
C. hoping D. hoped
此題的答案是 C不是A，其中的現在分詞短語 hoping to catch the early bus 用作伴隨狀語。
(5) He spent every minute he could _____ spoken English.
A. practise B. to practise
C. practising D. practised
此題答案選 C，這與前面動詞 spent 的搭配有關，即 spend … (in) doing sth。若將此句補充完整，即為 He spent every minute he could spend in practising spoken English.
(6) Before going abroad he devoted all he could ____D____ his oral English.
A. improve B. to improve
C. improving D. to improving
此題答案選D，注意兩點：一是 devote … to … 是固定搭配，意為“把……貢獻給……”;二是其中的 to 是介詞，不是不定式符號，後接動詞時要用動名詞。
2. He knows nothing about it, so he can’t help _______ any of your work.
A. doing B. to do
C. being doing D. to be done
【陷阱】容易誤選B，根據 can’t help doing sth 這一結構推出。
【分析】其實答案應選A。比較以下結構：
can’t help to do sth = 不能幫助做某事
can’t help doing sth = 禁不住做某事，情不自禁地做某事
