① 定語從句的位置：放在名詞或代詞的後面。如：The man who has an umbrella in his hand is my uncle. (手上抓了一把雨傘的人是我的叔叔。)
② 語法術語的改變：被修飾的名詞或代詞稱為先行詞；引導定語從句的連線詞稱為關係詞,其中that、which、who稱為關係代詞,where、when、how稱為關係副詞。
關係代詞who、whom 和whose指人,分別在從句中作主語、賓語和定語。which指物that多指物, 有時也指人,它們在從句中可以作主語或賓語。定語從句中關係代詞作從句賓語時可以省略。This is the thief (that/who/whom) we have been looking for these days. (這個就是我們近日一直在找的小偷。) / Please find a room which is big enough for all of us to live in. (請找一間足夠大能住下我們全體的房間。)
關係副詞when或where引導定語從句時,它們在從句中分別作時間狀語和地點狀語。如：This is the room where they had a quarrel a week ago. (這是一個星期前他們吵架的房間。) / I can never forget the day when I first saw you. (我永遠不會忘記第一次見到你的日子。)
④ 限制性定語從句和非限制性定語從句。限制性定語從句在句中不能省略,否則主句意思就不完整。非限制性定語從句和主句之間往往用逗號分開,這種從句是一種附加說明,如果從句子中省去,也不致於影響主句的意思。如：She spent the whole evening talking about her latest book, which none of us had heard of. (她一個晚上都在談論她最近的書,我們一個人都沒有聽說過那本書。)
定語從句：在複合句中作定語用修飾句子中某一名詞或代詞的從句叫定語從句。
① 定語從句的位置：放在名詞或代詞的後面。如：The man who has an umbrella in his hand is my uncle. (手上抓了一把雨傘的人是我的叔叔。)
② 語法術語的改變：被修飾的名詞或代詞稱為先行詞；引導定語從句的連線詞稱為關係詞,其中that、which、who稱為關係代詞,where、when、how稱為關係副詞。
關係代詞who、whom 和whose指人,分別在從句中作主語、賓語和定語。which指物that多指物, 有時也指人,它們在從句中可以作主語或賓語。定語從句中關係代詞作從句賓語時可以省略。This is the thief (that/who/whom) we have been looking for these days. (這個就是我們近日一直在找的小偷。) / Please find a room which is big enough for all of us to live in. (請找一間足夠大能住下我們全體的房間。)
關係副詞when或where引導定語從句時,它們在從句中分別作時間狀語和地點狀語。如：This is the room where they had a quarrel a week ago. (這是一個星期前他們吵架的房間。) / I can never forget the day when I first saw you. (我永遠不會忘記第一次見到你的日子。)
④ 限制性定語從句和非限制性定語從句。限制性定語從句在句中不能省略,否則主句意思就不完整。非限制性定語從句和主句之間往往用逗號分開,這種從句是一種附加說明,如果從句子中省去,也不致於影響主句的意思。如：She spent the whole evening talking about her latest book, which none of us had heard of. (她一個晚上都在談論她最近的書,我們一個人都沒有聽說過那本書。)