導語：同位語和定語從句的區別是什麼?以下是小編為大家整理的文章，歡迎閱讀!希望對大家有所幫助!
1、從句所修飾詞的不同。
同位語從句所修飾詞通常是少數一些表示抽象意義的名詞，如belief , doubt , fact, hope , idea , news , possibility , thought , order , suggestion , wish ,answer , information , conclusion , decision , discovery , knowledge , law ,opinion , problem , promise , proof , question , report , truth , risk 等。
定語從句的先行詞可以指人、物等。
例如：
He has told us a fact that drinking too much does harm to our health.
他又告訴我們一個事實，過渡飲酒對健康有害。(同位語從句)
We have no idea that her mother was a professor ten years ago.
我們不知道她的母親十年前是個教授。(同位語從句)
This is the book that I bought yesterday.
這是我昨天買的那本書。(定語從句)
I will never forget the day when I joined the Party.
我將永遠不會忘記我入黨的那一天。(定語從句)
2. 連線詞的作用不同。
連線同位語從句的that只起連線作用，不在從句中擔任任何句子成分。whether 和how 可以引導同位語從句，但不能引導定語從句。關係代詞和關係副詞除了連線從句的作用外，還在定語從句中充當一定的句子成分，如主語、賓語、定語、表語等。引導定語從句的連線詞是關係詞，常見的關係代詞和關係副詞有that , which , who ,whose , whom , when , where , why , as，than, but 等。
The news that he wants to get is whether he will be sent to the countryside.
他所想得到的訊息是他是否將被派往農村。(定語從句，關係代詞that作從句get的賓語。)
Do you have a doubt whether she will be dismissed from school?
你懷疑她是否能被學校開除嗎?(同位語從句)
I have no idea how his parents were sad on hearing that their son was killed in the earthquake.
我不知道他的父母一聽到他在地震中陣亡是多麼悲傷!(同位語從句)
3. 從句作用的不同。
定語從句具有形容詞或副詞的特點，對先行詞起修飾、限定作用，描述先行詞的性質或特徵，與先行詞之間是所屬關係。同位語從句具有名詞的特點，對中心詞作進一步補充解釋，是中心詞的具體內容。
例如：
The man that you saw just now is my bother.
你剛才看到的`那個人是我的弟弟。(定語從句)
The suggestion that the meeting be put off proved right.
推遲會議的建議證明是正確得。(同位語從句)
The suggestion that he had made is that the meeting be put off.
他提出的建議推遲會議。(定語從句)
4. 正確理解和使用同位語從句，還應注意以下幾點：
A.分隔同位語從句：有時同位語從句與其先行詞被其它成分分隔開來，這種分隔主要出於修辭原因，即為了保持句子結構平衡，避免頭重腳輕。
The whole truth came out at last that he was a wolf in sheep‘s clothing .
真相終於大白了，他原來是隻披著羊皮的狼。
B.在某些名詞後的同位語從句中，其謂語動詞應用虛擬語氣形式：(should)+ 動詞原形。常見的名詞有advice , idea , order , demand ,plan , proposal , suggestion , request 等。例如：
The suggestion that a new bridge (should) be built was accepted .
採納了在這裡修建一座新橋的建議。
C.同位語從句的先行詞往往沒有複數形式。例如：
他要來教我們英語的訊息昨天我就聽說了。
(正)The message that he would teach us English reached me yesterday .
(誤)The messages that he would teach us English reached me yesterday .
最後我們在一起來做三道練習題:
1. Along with the letter was his promise ____ he would visit me this coming Christmas.
A. which B. that
C. what D. whether
2. The other day, my brother drove his car down the street at ____ I thought was a dangerous speed.
A. as B. which
C. what D. that
3. Luckily, we'd brought a road map without ____ we would have lost our way.
A. it B. that
C. this D. which
答案:1. B 2. B 3. D
