定語從句，一個簡單句跟在一名詞或代詞後(先行詞)進行修飾限定，就叫做定語從句。下面是小編為大家提供的關於介詞和非限制的定語從句，內容如下：
非限定性定語從句：
意義：
非限定性定語從句起補充說明作用，缺少也不會影響全句的理解。在非限制性定語從句的前面往往有逗號隔開，如
(1)The house,which I bought has a lovely garden. 我買的房子帶著個漂亮的花園。
(2)This novel, which I have read three times, is very touching. 這本我已經讀過三遍的小說很感人。
1.非限定性定語從句可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：
(1)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。
(2)Liquid water changes to vapor, which is called evaporation. 液態水變為蒸汽，這就叫做蒸發。
2. 在非限定定語從句中，有時as也可用作關係代詞，若as在從句中作主語，其引導的句子可以放在句首，也可以放在句中。例如：
(1)The boy has as much progress as we had expected. 正像我們所預料的那樣，這個男孩取得了大的進步。
(2) As everyone knows ,China is a beautiful country with a long history . 每個人都知道，中國是一個有著悠久歷史的美麗國家。
3. 在非限定性定語從句中，不能用從句做主語
(1)The boys ，who are playing football ，are from Class One. 在踢足球的男孩們是一班的。
(2)I helped an old man ，who lost his way ，yesterday . 昨天，我幫助了一個迷路的.老人。
介詞的正確選擇：
1. 根據後面動詞和介詞的搭配關係選擇。如：
①This is not the book of which the teacher spoke in class. (speak of 意為“談論”，相當於talk about)
②The two things of which they felt proud were Jim’s gold watch and Della’s hair. (be / feel proud of 為固定短語，意為“以……自豪”。)
2. 根據前面的名詞的搭配關係選擇。如：
①I’ll never forget the day on which I first met him. (表示具體的某一天，介詞用on)
②The boy pointed to the direction in which he would run. (“朝……方向”，介詞用in)
3. 有時需同時考慮動詞和介詞的搭配關係及介詞和名詞的搭配關係。如：
The clever boy made a hole in the wall, through which he could see what was happening inside the house.
