初中英語裡有三大從句，它們分別是狀語從句、賓語從句和定語從句。我們首先應該弄懂什麼叫從句，從句是複合句中具有分屬地位的一種分句，是把整個句子當作複合句中的一個成分來用，整個從句在複合句中的作用就相當於一個詞、一個短語。從句本身就是一個句子，有從句本身的主語和謂語動詞，從句前面要有一個引導詞或連詞，把整個從句「統領」起來，當然有時這個引導詞或連詞可省略，在「暗中統領」著從句。
我們來認識一下
Where did you study beforeyou came to this school?
上面這個句子，既有主句Where did you study，又有從句before you came to this school,包含主句、從句的句子就叫複合句。before是從句的引導詞，後面一個you 是從句的主語，came是從句的謂語動詞。整個從句before you came to this school的作用就相當於last year或two years ago這樣的詞或短語，表示主句動作發生的時間。
在複合句中充當狀語的從句叫狀語從句，充當賓語的從句叫賓語從句，充當定語的從句叫定語從句。
關於這三種從句，是初中英語學習中的難點，相當一部分學生是無法完全突破的，同時也是重點，是很常考的考點，幾乎每個省市的中考題中都有它們的影子。很多學生反映沒辦法弄懂，心裡害怕含有從句的長句，不能正確理解、運用它們。下面，我試圖從六個維度出發，來跟大家探討一下這三大從句：
一、從句的位置
理解含有從句的長句，首先一種能力是你要能夠看出它是什麼從句。要達到一眼就能看出是什麼從句的程度，就必須了解從句的位置和從句的含義、作用。狀語從句可位於主句之後也可位於主句之前，用逗號隔開。如：
I was watching TV when he came in last night.
=When he came in last night,I was watching TV.
賓語從句位於動詞或介詞之後作賓語，具體有下列幾種情況：
1）位於及物動詞（vt.）之後；
2）位於及物動詞（vt.）+sb之後；
3）位於介詞（prep.）之後；
4）位於連繫動詞+形容詞（adj.）之後；
5）位於say/explain to sb之後。
1. I think（that）you are right.
2. He told mewhere he would go for vacation.
3. This book is abouthow we can learn English well.
4. I am afraid (that) he isn’t here at the moment.
5. He said to me that he had been to Beijing twice.
定語從句位於名詞或代詞（叫先行詞）之後，不過有時候在先行詞與定語從句之間可插入副詞或介詞短語等。
1. Do you know the man(先行詞）（who/whom/that）our head teacher is talking to?
2. Is there anything(先行詞）(that)I can do for you?
3. Do you still remember the teacher(先行詞）in that school who/that taught us math when we were in Grade 6?
二、從句的含義、作用
了解了從句的位置，基本上就能幫助我們判斷這個從句是什麼從句，但也有特殊情況，大家來判斷一下下面兩句中分別包含了什麼從句：
1. The teacher had a talk with the studentthat failed the exam this time.
2. The teacher told the studentthat he should study harder.
如果不把握好從句的含義、作用，只是根據從句的位置判斷從句的類型，很可能就會出現錯誤。上面兩句中從句都是位於名詞the student後面，但第一句才是定語從句，從句中所表示的是對其前面的名詞the student進行修飾限定。而第二句是賓語從句，從句中所表示的是主句謂語動詞told的內容，the student是間接賓語，而賓語從句作told的直接賓語。
所以，在理解三種從句時一定要注意從句的作用：狀語從句在複合句中作狀語，對主句的動詞、形容詞、副詞加以修飾;賓語從句在複合句中作主句動詞或介詞的賓語，表示主句動詞或介詞的具體內容;定語從句作定語，對前面的名詞或代詞（即先行詞）加以修飾限定。
三、從句的引導詞
懂得了是什麼從句，我們就較容易選出合適的引導詞來「統領」這個從句。當然，我們還必須知道這三種從句分別有哪些引導詞。狀語從句有九種，它們的引導詞分別是：
1）引導時間狀語從句的有：when/while/as/before/after/till/until/as soon as/since/once/every time/next time/the first time/the last time/by the time。
2）引導原因狀語從句的有：because/as/since/now that。
3）引導條件狀語從句的有：if/unless/as long as。
4）引導比較狀語從句的有：than/as...as。
5）引導方式狀語從句的有：as/as if/as though。
6）引導地點狀語從句的有：where /wherever。
7）引導讓步狀語從句的有：though/although/even if/even though/whenever=no matter when/whatever=no matter what/whoever=no matter who/however=no matter how/whether...or...。
8）引導目的狀語從句的有：so that/in order that。
9）引導結果狀語從句的有：so...that.../such...that...。
狀語從句的引導詞在狀語從句中不充當任何成分，只是起著引導從句的作用。
選擇狀語從句的引導詞主要根據主句、從句的意思來確定。
賓語從句的引導詞有三類：
一）連詞that(當把陳述句用作賓語從句時，用that引導，that在賓語從句中不充當成分，可省略）。如：
1. 把直接引語改為間接引語
He said to me,「I will go to the museum tomorrow」.
He told me that he would go to the museum the next day.
2. 合併成複合句
I’m sure. Maria can pass the exam this time.
I’m sure that Maria can pass the exam this time.
二）連詞if/whether（當把一般疑問句用作賓語從句時，用if或whether引導，if/whether在賓語從句中不充當成分，但不能省略）。
1.把直接引語改為間接引語
He said to me,「Are you interested in English?」
He asked me if/whether I was interested in English.
2.合併成複合句
Do you know? Does she like Beijing Opera?
Do you know if/whether she likes Beijing Opera?
注意: 一般情況下,if 和 whether 可以互換,但以下 3 種情況只能用 whether:
(1)與 or not 連用。 如:He asked me whether or not I was coming. 他問我是否要來。
(2)在介詞之後。 如:It depends on whether it is going to rain. 這要看天氣是否會下雨。
(3)在不定式之前。 如:We haven't decided whether to go there. 我們還沒有決定是否去那裡。
三）連接代詞或連接副詞（當把特殊疑問句用作賓語從句時，用連接代詞或連接副詞引導,這裡的連接代詞、連接副詞實際上就是特殊疑問句中的疑問代詞、疑問副詞，注意連接代詞、連接副詞在賓語從句中充當某一成分，不能省略）。如：
1. 把直接引語改為間接引語
He said to me,「where does Maria live?」
He asked me where Maria lived.
2. 合併成複合句
She asked. How many times has Jack been to Hong Kong?
She asked how many times Jack had been to Hong Kong.
選擇賓語從句的引導詞既要根據主句謂語動詞的性質，也要根據賓語從句的意思（看看賓語從句是否缺少什麼）。
當主句謂語動詞為陳述性質（即肯定語氣）如say/think/believe/suggest/advise/be sure/hope/wish等時，引導詞用that;當主句謂語動詞為疑問性質（即不肯定語氣）如ask/wonder等時，引導詞用if/whether/連接代詞/連接副詞。如：
1.I believethat he is right.
2.I am sure that he can pass the exam.
3.I am not surethat/if he can pass the exam.
4.I wonderwhere he lives.
5.I don』t know what I shall do（及物動詞）next.
定語從句的引導詞有兩類：
一）關係代詞
當先行詞表示人時，引導詞用who/that(在從句中作主語或賓語）/whom（在從句中只作賓語）/whose（在從句中作定語，後接名詞）;
當先行詞表示事物時，引導詞用which/that(在從句中作主語或賓語）/whose(在從句中作定語，後接名詞）。
1. Do you know the person who/that is standing under the tree?
2. I prefer the bookwhich/that you showed me just now.
3. Look at the building whose walls(名詞）are yellow.
注意：1）what和how不能引導定語從句；
2）引導詞在定語從句中作賓語時可省略，但引導詞所代替的那個賓語應該去掉；
如：Do you know the man (who/that/whom)I talked to just now?
在talked to後面不能再來一個賓語him,因為已經用引導詞who/that/whom代替him作talked to的賓語了。
3) 如果把介詞提到引導詞前面時，先行詞表示人，引導詞只用whom,先行詞表示事物，引導詞只用which,即人+介詞+whom和事物+介詞+which。如上面一句也可以表達成Do you know the man to whom I talked just now?
4) 先行詞是 a way/the way/ways時,引導詞可用that/in which或省略引導詞。
5) 下列情況只能用 that (不用 which) 來指代物
(1)先行詞為 all, much, little, something, anything, everything, nothing 等不定代詞時。如:
I will do everything that I can do to help you. 我將做我能做的一切事情來幫助你。
(2)先行詞是最高級或者被形容詞的最高級修飾時。 如:
This is the most important task that should be finished soon. 這是必須馬上完成的最重要的任務。
(3)先行詞為數詞或被序數詞修飾時。 如:
You are the first men that like the kind of book. 你們是第一批喜歡這種書的人。
(4)先行詞中既有人又有物時。 如:
We were deeply impressed by the teachers and schools that we had visited. 我們訪問過的老師和學校給我們留下了很深的印象。
(5)當先行詞前有 the one, the only, the last, the very, any, few, little, no, all 等詞修飾時,引導詞只能用
that。如:
He is the only person that knows the truth. 他是唯一知道真相的人。
(6)當主句中已經含有疑問詞 who 或者 which 時,只用 that。 如:
Which is the bike that you lost? 哪一輛是你丟的自行車?
6) 下列情況只能用 who (不用 that) 來指代人
(1)先行詞是 one, ones, anyone 時,適宜用 who。 如:
One who has nothing to fear dares to tell the truth. 一個無所畏懼的人敢於說實話。
Don't tell anyone about the news who shouldn’t be told. 別告訴不該告訴的人任何消息。
(2)當 those 作先行詞指人時,引導詞只能用 who。 如:
Those who respect others are often respected by others. 尊敬別人的人也常常受人尊敬。
(3)當先行詞有較長的後置定語時,適宜用 who。 如:
I met a foreigner in the street who could speak Chinese well. 我在街上遇到一位可以把中文說得很好的外
國人。
(4)有兩個定語從句,其中一個關係代詞已經使用了 that,另一個宜用 who。 如:
The boy that you met last night is her brother who can make kites. 你昨晚遇到的那個男孩是她的哥哥,他會製作風箏。
(5)在 there be 開頭的句子中用 who。 如:
There is an old man who wants to see you. 有一個老人很想見你。
(6)當主語是 I, he, you, they 等時,常用於諺語、格言中,只能用 who。 如:
He who plays with fire gets burned. 玩火者自焚。
7) 非限制性定語從句不能用that引導。
二）關係副詞（在定語從句中作狀語）（高中階段學習）
當先行詞表示地點時，引導詞用where;
當先行詞表示時間時，引導詞用when;
當先行詞表示原因時，引導詞用why。
選擇定語從句的引導詞既要根據先行詞表示什麼，也要根據引導詞在定語從句中的作用來確定。試對比：
1. I still remember the school which/that（作從句謂語的賓語） I visited(及物動詞）last year.
2. I still remember the school where（在從句中作狀語） I taught（不及物動詞） for ten years.
四、從句的語序
狀語從句、賓語從句、定語從句都要用陳述句語序。
在狀語從句中，因為引導詞在從句中不充當成分，所以狀語從句的構成是：引導詞+主語+謂語動詞+...。
賓語從句的構成有下列幾種情況：
1）that/if/whether+主語+謂語動詞+...
2）作主語的連接代詞who/what/which+謂語動詞+...
I want to know what made him so angry.
3）作賓語、狀語、表語、賓補的連接代詞或連接副詞+主語+謂語動詞+...
Can you tell me when you were born?
4）作主語的定語的連接代詞whose/what/which/how many/how much+名詞+謂語動詞+...
The head teacher wonders whose fathers work in the hospital.
5）作非主語的定語的連接代詞whose/what/which/how many/how much+名詞+主語+謂語動詞+...
The farmer wanted to know how many apples the boy had picked.
對於定語從句，因為引導詞在從句中的作用不同，因此定語從句的構成也有幾種情況：
1）作主語的引導詞+謂語動詞+...
Do you know the man who/that is talking to our English teacher?
2) 作主語的定語的引導詞whose+名詞+謂語動詞+...
I know the man whose son studies in the famous university.
3) 作非主語的定語的引導詞whose+名詞+主語+謂語動詞+...
I visited the man whose son I had lived with for three years yesterday.
4) 作賓語、狀語的引導詞who/whom/which/that/where/when/why+主語+謂語動詞+...
I like music which/that I can dance to.
五、從句的時態
狀語從句的時態受主句時態的影響，狀語從句與主句的時態對應有四條時態原則：
一) 主句用現在時，狀語從句用現在時
1. He often doesmorning exercises after he gets up.
2. Although she studieshard,she doesn』t do well in all her subjects.
二）主句用過去時，狀語從句用過去時
1.I sawhim when I looked up just now.
2.We were walkingin the street when we met her yesterday evening.
3.We mether when(或while)we were walking in the street yesterday evening.
4.He was doinghomework when(或while)his brother was watching TV yesterday.
三）主句用一般將來時或祈使句或含情態動詞，狀語從句用一般現在時
這條時態原則（也就是平常所說的「主將從現」）考得最多，那麼，要知道這條時態原則適用於什麼情況，這條時態原則適用於時間狀語從句（since所引導的除外）和條件狀語從句。
1. Wewill go hiking if it doesn』t rain tomorrow.
2. Please cometo my home when you have time.
3. Youcan catch up with others as long as you study hard enough.
四）主句用現在完成時，since從句用一般過去時
He has workedin this company since he graduated from a university.
賓語從句的時態也受主句時態的影響，賓語從句與主句的時態對應有兩條時態原則：
一）主句用現在時或將來時，賓語從句可根據實際情況用任何時態
1. Idon』t know where he lives.
2. The teacher wonderswhat they are doing.
3. I believehe will come to join us.
4. Iwant to know how many times you have been there.
5. Doyou know why they stayed up so late last night?
二）主句用過去時，賓語從句也要用過去時態的某種形式
1. He asked if you would go with us.
2. I knew they were playing games this time yesterday.
3. She said she had been to Beijing twice.
注意：如果賓語從句表示的是普遍真理，即使主句用了過去時，賓語從句照樣要用一般現在時。如：
The teacher told us that the earth goes round the sun.
定語從句的時態不受主句時態的影響，根據定語從句動作所發生的時間進行確定,但有時要注意與主句動作的先後關係。
1. This is the school where we studied for three years.
2. He is the boy who is handsome.
3. He is the boy who ran fastest in the race.
4. They talked about the school which/that they will build next year.
5. They were talking about the place which/that they would visit the next day.
6. They were talking about the place which/that had attracted them so much.
六、從句中謂語的數
在從句中，從句謂語的數與從句主語相一致，這點大家都懂。問題是在賓語從句和定語從句中，因為引導詞本身可以作從句的主語，而引導詞本身是看不出是單數還是複數的，這就要引起注意。
1. I don’t know who teaches us physics.
2. I wonder who are going there.
3. Can you tell me what makes you so sad?
上面三句含有賓語從句，在賓語從句中，who/which作從句主語時，從句謂語有可能是單數，也有可能是複數，但what作從句主語時，從句謂語用單數。
4. This is the music (which/that)I aminterested in.
5. I love musicwhich/that is popular.
6. I love songswhich/that are popular.
上面三句含有定語從句，在定語從句中，當引導詞在從句中作主語時，定語從句的謂語的數要與先行詞一致。
上面我們從六個維度出發，區分了初中階段所學的三種從句。只要大家在學習、使用這三種從句時，緊緊把握好這六個維度，靈活處理，定能真正學好這三大從句。