定語從句：在復(fù)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：放在名詞或代詞的后面.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(shù)語的改變：被修飾的名詞或代詞稱為先行詞；引導(dǎo)定語從句的連接詞稱為關(guān)系詞,其中that、which、who稱為關(guān)系代詞,where、when、how稱為關(guān)系副詞.
③ 關(guān)系代詞或關(guān)系副詞的作用：
關(guān)系代詞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(shí)也指人,它們在從句中可以作主語或賓語.定語從句中關(guān)系代詞作從句賓語時(shí)可以省略.This is the thief (that/who/whom) we have been looking for these days. (這個(gè)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?nèi)w的房間.)
關(guān)系副詞when或where引導(dǎo)定語從句時(shí),它們在從句中分別作時(shí)間狀語和地點(diǎn)狀語.如：This is the room where they had a quarrel a week ago. (這是一個(gè)星期前他們吵架的房間.) / I can never forget the day when I first saw you. (我永遠(yuǎn)不會(huì)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(hào)分開,這種從句是一種附加說明,如果從句子中省去,也不致于影響主句的意思.如：She spent the whole evening talking about her latest book, which none of us had heard of. (她一個(gè)晚上都在談?wù)撍罱臅?我們一個(gè)人都沒有聽說過那本書.)
[注解]
1、關(guān)系代詞只能用that的情況：當(dāng)先行詞是指事物的不定代詞(all, anything等),或先行詞部分含有最高級,或含有序數(shù)詞時(shí),不能用其他的關(guān)系代詞,只能用that. 如：All that Lily told me seems untrue. (Lily告訴我的話似乎不真實(shí).) / Can you give me anything that has no sugar inside? (能不能給我點(diǎn)里面沒有糖的東西?) / This is the first two-story bus that runs in our city. (這是第一輛運(yùn)行于我市的雙層公交車.)
2、關(guān)系代詞在從句中作主語時(shí)一般用who(指人)、that(指物),而不用that指人或用which指物. 如：Do you know the woman who is weeping in the corner? (你認(rèn)識(shí)那個(gè)在角落里哭泣的女人嗎?) / Do not tell me any words that have nothing to do with me. (跟我無關(guān)的話,請一個(gè)字也不要說.)
3、關(guān)系代詞作從句的賓語時(shí),常用which或whom,較少使用that或who,而且,關(guān)系代詞常常省略.如：Tom’s father was the first parent whom our teacher talked to. (Tom的父親是我們老師第一個(gè)談話的人.)
4、當(dāng)關(guān)系代詞緊跟在介詞后面時(shí),必須用which或whom,而當(dāng)介詞移到句尾時(shí),則又可以使用that或who. 如：This is the room in which Miss Li once lived. (= This is the roomMiss Li once lived in.) (這是李小姐曾經(jīng)居住過的房間.)
(5) 主語從句：在句子中充當(dāng)句子主語的從句叫主語從句.位于謂語動(dòng)詞之前.通常由that,whether以及疑問連詞引導(dǎo).一般情況下,常用it替代主語從句,而將主語從句移到句尾.如：When we should start is still a question. (我們該在什么時(shí)候開始還是個(gè)問題呢.)