? ? ? 在雅思寫作中，一般的簡(jiǎn)單句會(huì)用一個(gè)形容詞做定語來修飾一個(gè)名詞，但當(dāng)定語成分太過復(fù)雜而不能只用單個(gè)形容詞擔(dān)當(dāng)時(shí)，就要借助于一個(gè)句子來做定語修飾名詞。
　　像這樣由句子擔(dān)當(dāng)定語，對(duì)被修飾的先行詞進(jìn)行有限定制約，使該詞的含義更具體，更明確，我們稱之為限定性定語從句，下面我們結(jié)合例句進(jìn)行對(duì)比學(xué)習(xí)：
　　a)I don’t like lazy people(形容詞做定語放在名詞前面).
　　b)I don’t like the people who never keep their words. 我不喜歡從不遵守諾言的人.
　　在限定性定語從句中，有兩個(gè)比較重要的概念。以b句為例,獨(dú)立主句是：I don’t like the people;定語從句為“who never keep their words”，相當(dāng)于一個(gè)形容詞，做定語修飾名詞“the people”， 且從句和主句是由who來連接的。在定語從句中，“the people”被稱為先行詞，指被定語從句所修飾或限制的對(duì)象。“who”被稱為關(guān)系詞即重復(fù)指代先行詞，并在定語從句中充當(dāng)一定成分的連詞。
　　從上面的解析不難看出，關(guān)系詞在限定性定語從句中很重要，是連接主句和從句的關(guān)鍵。關(guān)系詞可以分為關(guān)系代詞和關(guān)系副詞，下面我們一起來進(jìn)行具體的學(xué)習(xí)。
　　I.關(guān)系代詞主要有：who, whom, whose, which, that.
　　A. 當(dāng)先行詞為人時(shí)，可用關(guān)系代詞who,whom,whose 和that.
　　a. 若關(guān)系代詞在從句中做主語時(shí)，選用 who 或that.
　　eg：The woman is a responsible teacher who /that is loved by her students.
　　 ? = The woman is a responsible teacher and she is loved by her students.
　　b. 若關(guān)系代詞在從句中做賓語時(shí)，選用 whom(首選),who 或that.
　　eg: The girl whom we are talking about is a good friend of us.
　　c. 若關(guān)系代詞在從句中做定語,表示人的所有關(guān)系時(shí)，選用 whose 或of whom.
　　eg:I know a friend whose sister is a famous dancer.
　　= I know a friend. His sister is a famous dancer. (whose 代替了his,指人 friend)
　　B.當(dāng)先行詞為物時(shí)，可用關(guān)系代詞which, that 或whose.
　　a. 若關(guān)系代詞在從句中做主語或賓語時(shí)，選用 which 或that.
　　Eg:These are the trees which / that are destroyed in the fire(做主語).
　　b. 若關(guān)系代詞在從句中做定語,表示物的所有關(guān)系時(shí)，選用 whose 或of which.
　　Eg:The children saw an elephant whose legs were hurt badly.
　　綜上所述，當(dāng)先行詞為人和物時(shí)，若在從句中做主語或是賓語，這時(shí)可用選用關(guān)系代詞that，做定語時(shí)用whose.
　　II. 關(guān)系副詞主要有：where,when 和why.
　　A. 當(dāng)先行詞為表示地點(diǎn)的名詞時(shí)，定語從句由副詞where引導(dǎo).
　　In the sixth century BC, ancient Greece was a country where there were a lot of new ideas.
　　B. 當(dāng)先行詞為表示時(shí)間的名詞時(shí)，定語從句由副詞when引導(dǎo).
　　Plato lived at a time when philosophy was very fashionable.
　　C. 當(dāng)先行詞為表示原因的名詞時(shí)，定語從句由副詞why引導(dǎo).
　　Can you tell me the reason why you lied to me?
　　需要注意的是，限制性定語從句不能被省略，否則句意就不完整，例如:I met someone who said he knows you.