從句子結(jié)構(gòu)上來說,句子有三種：簡(jiǎn)單句、并列句和復(fù)合句.簡(jiǎn)單句有一個(gè)主語(yǔ)或多個(gè)主語(yǔ)和一個(gè)謂語(yǔ)；一個(gè)主語(yǔ)和多個(gè)謂語(yǔ).并列句是由并列連詞連接的兩個(gè)或多個(gè)簡(jiǎn)單句.復(fù)合句指的是含有兩個(gè)或更多的主謂結(jié)構(gòu)的句子,其中有一個(gè)（或更多）主謂結(jié)構(gòu)充當(dāng)句子的某一（些）成分,如主語(yǔ)、賓語(yǔ)、表語(yǔ)、定語(yǔ)、狀語(yǔ)、同位語(yǔ)等.主語(yǔ)從句、賓語(yǔ)從句、表語(yǔ)從句、同位語(yǔ)從句、定語(yǔ)從句和狀語(yǔ)從句都屬于復(fù)合句.
一、狀語(yǔ)從句：

狀語(yǔ)從句 Adverbial Clause,從句用作狀語(yǔ)稱為狀語(yǔ)從句.根據(jù)用途,狀語(yǔ)從句可分為時(shí)間、地點(diǎn)、原因、條件、方式、讓步、結(jié)果、目的等狀語(yǔ)從句.

I. 時(shí)間狀語(yǔ)從句
時(shí)間狀語(yǔ)從句表示時(shí)間,常用的關(guān)聯(lián)詞有when, until, as, after, before, once, since, as long as, whenever等等.
例: 1) When you cross a main road, you must be careful.
2) He went out to play football after he had finished his homework.
3) Wait until you are called.
4) I can't recognize you. You are so changed since last we met.
5) He didn't go to school until he was eleven.
You can use my house as long as you are careful.
He is so terrible once he is drunk.
I listen to the radio while I walk every evening.

II. 地點(diǎn)狀語(yǔ)從句
地點(diǎn)狀語(yǔ)從句表示地點(diǎn),常用的關(guān)聯(lián)詞有where, wherever, anywhere等.
例如：1) Put it where you found it.
2) Sit down wherever you like.
3) Anywhere she goes, he goes too.

III. 原因狀語(yǔ)從句
原因狀語(yǔ)從句表示原因或理由,常用的關(guān)聯(lián)詞有because, as, since, in case等.
1) I eat ice-cream so much because I like sweet food.
2) As I didn't know the way, I asked a policeman.
3) Since you won't help me, I'll ask someone else.
I'll take my raincoat in case it rains. (in case it rains = because it may rain)我將帶上雨衣,以防下雨.

IV. 條件狀語(yǔ)從句
條件狀語(yǔ)從句表示真實(shí)的或現(xiàn)實(shí)的條件,引導(dǎo)從句所用的關(guān)聯(lián)詞有if, unless, suppose, in case(that), in the event (that), as (so) long as等等.
1) If it snows tomorrow, we will build a snowman.
You'll be late, unless you hurry.
3) Suppose we are late, what will he say? (suppose從句必須放在主句之前) 我們?nèi)绻t到了,他會(huì)說什么?
4) In the event that our team wins, there will be a party.
5) In case it rains, do not expect me. 如果下雨,就不要等我了.
6) He will do anything as(so) long as it is interesting. 只要好玩,他什么都愿意做.

V. 方式狀語(yǔ)從句
方式狀語(yǔ)從句表示動(dòng)作的方式,回答How的問題,常用關(guān)聯(lián)詞as, as if, as though, the way(that), in the way(that)等引導(dǎo),一般置于主語(yǔ)之后.
Do as I say. I did just as you told me. 照我說的去做.我就是照你說的去做的.
He acts as if/as though he is the owner. 他行為舉止好象是這兒的主人似的.
They did it in a way that I had never seen before. 他們以我從沒見過的方式行事.
I was never allowed to sing the way I wanted to. 我從未被允許用自己想用的方式唱歌.

VI. 讓步狀語(yǔ)從句
讓步狀語(yǔ)從句表示“雖然、盡管、即使”等概念,使句子具有對(duì)比的因素.常用的關(guān)聯(lián)詞有although, though, even if, even though, not that(=although…not)等,置于主語(yǔ)之前或后.
1) Although you feel very ill right now, this is still a common disease.
2) Though he has lived for years in London, he writes in French.
3) We intend to go U.S., even if air fares are expensive.
4) Even though fruits are good, you can't live with fruits only.
5) I'm OK now, not that I slept (although I did not sleep) very well last night.

VII. 結(jié)果狀語(yǔ)從句
結(jié)果狀語(yǔ)從句表示結(jié)果, 常由連詞so…that, such(a/an)…that, so that, such that等引導(dǎo),置于主語(yǔ)之后.
She was so frightened about the dog that she cried.
The news worried him so much that he didn't sleep at all for the whole night.
He is such a wonderful joker that you can't help laughing.
They are such wonderful players that no one can beat them.
We arrived early, so that we got good seats.
The weather was such that I couldn't go out.

VIII. 目的狀語(yǔ)從句
目的狀語(yǔ)從句表示目的,回答what for或 for what purpose的問題,常用關(guān)聯(lián)詞so that, in order that等引導(dǎo),一般置于主語(yǔ)之后.目的狀語(yǔ)從句中的謂語(yǔ)動(dòng)詞常由“情態(tài)動(dòng)詞+動(dòng)詞原形”構(gòu)成.
Ships carry lifeboats so that people can escape if the ship sinks.
They wrote the notice in several languages so that foreigners could understand it.
We carved their names on the stone in order that people should always remember them.
They risk their lives so that/in order that they may support their kids.
二、定語(yǔ)從句

定語(yǔ)從句（Attributive Clauses）在句中做定語(yǔ),修飾一個(gè)名詞或代詞,被修飾的名詞,詞組或代詞即先行詞.定語(yǔ)從句通常出現(xiàn)在先行詞之后,由關(guān)系詞（關(guān)系代詞或關(guān)系副詞）引出.

關(guān)系代詞有：who, whom, whose, that, which等.
關(guān)系副詞有：when, where, why等

1. 關(guān)系代詞引導(dǎo)的定語(yǔ)從句

關(guān)系代詞所代替的先行詞是人或物的名詞或代詞,并在句中充當(dāng)主語(yǔ)、賓語(yǔ)、定語(yǔ)等成分.關(guān)系代詞在定語(yǔ)從句中作主語(yǔ)時(shí),從句謂語(yǔ)動(dòng)詞的人稱和數(shù)要和先行詞保持一致.

1）who, whom, that 這些詞代替的先行詞是人的名詞或代詞,在從句中所起作用如下：
Is he the man who/that wants to see you?
他就是你想見的人嗎?（who/that在從句中作主語(yǔ)）
He is the man whom/ that I saw yesterday.
他就是我昨天見的那個(gè)人.（whom/that在從句中作賓語(yǔ)）

2) Whose 用來指人或物,(只用作定語(yǔ), 若指物,它還可以同of which互換）,例如：
They rushed over to help the man whose car had broken down.
那人車壞了,大家都跑過去幫忙.
Please pass me the book whose (of which) cover is green.
請(qǐng)遞給我那本綠皮的書.

3） which, that 它們所代替的先行詞是事物的名詞或代詞,在從句中可作主語(yǔ)、賓語(yǔ)等,例如： A prosperity which / that had never been seen before appears in the countryside.
農(nóng)村出現(xiàn)了前所未有的繁榮.（which / that在句中作賓語(yǔ)）
The package (which / that) you are carrying is about to come unwrapped.
你拿的包快散了.(which / that在句中作賓語(yǔ))

2. 關(guān)系副詞引導(dǎo)的定語(yǔ)從句

關(guān)系副詞可代替的先行詞是時(shí)間、地點(diǎn)或理由的名詞,在從句中作狀語(yǔ).
1）when, where, why 關(guān)系副詞when, where, why的含義相當(dāng)于"介詞+ which"結(jié)構(gòu),因此常常和"介詞+ which"結(jié)構(gòu)交替使用.例如：
There are occasions when (on which) one must yield. 任何人都有不得不屈服的時(shí)候. Beijing is the place where (in which) I was born. 北京是我的出生地.
Is this the reason why (for which) he refused our offer?
這就是他拒絕我們幫助他的理由嗎?

2）that代替關(guān)系副詞that可以用于表示時(shí)間、地點(diǎn)、方式、理由的名詞后取代when, where, why和"介詞+ which"引導(dǎo)的定語(yǔ)從句,在口語(yǔ)中that常被省略.例如：
His father died the year (that / when / in which) he was born.
他父親在他出生那年逝世了.
He is unlikely to find the place (that / where / in which) he lived forty years ago.
他不大可能找到他四十年前居住過的地方

3. 判斷關(guān)系代詞與關(guān)系副詞
方法一： 用關(guān)系代詞,還是關(guān)系副詞完全取決于從句中的謂語(yǔ)動(dòng)詞.及物動(dòng)詞后面無(wú)賓語(yǔ),就必須要求用關(guān)系代詞；而不及物動(dòng)詞則要求用關(guān)系副詞.例如：
This is the mountain village where I stayed last year.
I'll never forget the days when I worked together with you.

習(xí)慣上總把表地點(diǎn)或時(shí)間的名詞與關(guān)系副詞 where, when聯(lián)系在一起.

方法二： 準(zhǔn)確判斷先行詞在定語(yǔ)從句中的成分(主、謂、賓、定、狀),也能正確選擇出關(guān)系代詞/關(guān)系副詞.
4. 限制性和非限制性定語(yǔ)從句
1) 定語(yǔ)從句有限制性和非限制性兩種.限制性定語(yǔ)從句是先行詞不可缺少的部分,去掉它主句意思往往不明確；非限制性定語(yǔ)從句是先行詞的附加說明,去掉了也不會(huì)影響主句的意思,它與主句之間通常用逗號(hào)分開,例如：
This is the house which we bought last month.
這是我們上個(gè)月買的那幢房子.（限制性）
The house, which we bought last month, is very nice.
這幢房子很漂亮,是我們上個(gè)月買的.（非限制性）

2) 當(dāng)先行詞是專有名詞或物主代詞和指示代詞所修飾時(shí),其后的定語(yǔ)從句通常是非限制性的,例如： Charles Smith, who was my former teacher, retired last year.
查理·史密斯去年退休了,他曾經(jīng)是我的老師.
My house, which I bought last year, has got a lovely garden.
我去年買的的那幢房子帶著個(gè)漂亮的花園.
This novel, which I have read three times, is very touching.
這本小說很動(dòng)人,我已經(jīng)讀了三遍.

3) 非限制性定語(yǔ)從句還能將整個(gè)主句作為先行詞, 對(duì)其進(jìn)行修飾, 這時(shí)從句謂語(yǔ)動(dòng)詞要用第三人稱單數(shù),例如：
He seems not to have grasped what I meant, which greatly upsets me.
他似乎沒抓住我的意思,這使我心煩.
Liquid water changes to vapor, which is called evaporation.
液態(tài)水變?yōu)檎羝?這就叫做蒸發(fā).

說明：關(guān)系代詞that和關(guān)系副詞why不能引導(dǎo)非限制性定語(yǔ)從句.

5. 介詞+關(guān)系詞
1）介詞后面的關(guān)系詞不能省略.
2）that前不能有介詞.
3） 某些在從句中充當(dāng)時(shí)間,地點(diǎn)或原因狀語(yǔ)的"介詞+關(guān)系詞"結(jié)構(gòu)可以同關(guān)系副詞when 和where 互換.
This is the house in which I lived two years ago.
This is the house where I lived two years ago.
Do you remember the day on which you joined our club?
Do you remember the day when you joined our club?

6. as, which 非限定性定語(yǔ)從句
由as, which 引導(dǎo)的非限定性定語(yǔ)從句,as和which可代整個(gè)主句,相當(dāng)于and this或and that.As一般放在句首,which在句中.
as 和which在引導(dǎo)非限制性定語(yǔ)從句時(shí),這兩個(gè)關(guān)系代詞都指主句所表達(dá)的整個(gè)意思,且在定語(yǔ)從句中都可以作主語(yǔ)和賓語(yǔ).但不同之處主要有兩點(diǎn)：
(1） as 引導(dǎo)的定語(yǔ)從句可置于句首,而which不可.
(2） as 代表前面的整個(gè)主句并在從句中作主語(yǔ)時(shí),從句中的謂語(yǔ)必須是系動(dòng)詞；若為行為動(dòng)詞,則從句中的關(guān)系代詞只能用which.
7. 先行詞和關(guān)系詞二合一
1)Whoever spits in public will be punished here. (Whoever 可以用 anyone who 代替)
2)The parents will use what they have to send their son to technical school. (what 可以用all that代替)

8. what/whatever;that/what; who/whoever
1）what = the thing which；whatever = anything
2) who= the person that whoever= anyone who
3) that 和 what
當(dāng)that引導(dǎo)定語(yǔ)從句時(shí) ,通常用作關(guān)系代詞,而引導(dǎo)名詞性從句時(shí),是個(gè)不充當(dāng)任何成分的連接詞.賓語(yǔ)從句和表語(yǔ)從句中的that?？墒÷?What只能引導(dǎo)名詞性從句, 用作連接代詞,作從句的具體成分,且不能省略.
9. 關(guān)系代詞that 的用法
1）不用that的情況
a) 在引導(dǎo)非限定性定語(yǔ)從句時(shí).
b) 介詞后不能用.
2) 只能用that作為定語(yǔ)從句的關(guān)系代詞的情況
a) 在there be 句型中,只用that,不用which.
b) 在不定代詞,如：anything, nothing, the one, all, much, few, any, little等作先行詞時(shí),只用that,不用which.
c) 先行詞有the only, the very修飾時(shí),只用that.
d) 先行詞為序數(shù)詞、數(shù)詞、形容詞最高級(jí)時(shí),只用that.
e) 先行詞既有人,又有物時(shí),只用that.
三、名詞性從句：

在句子中充當(dāng)主語(yǔ)、賓語(yǔ)、表語(yǔ)與同位語(yǔ)的句子分別叫做主語(yǔ)從句、賓語(yǔ)從句、表語(yǔ)從句和同位語(yǔ)從句, 這些統(tǒng)稱為名詞性從句.

（一）主語(yǔ)從句
在復(fù)合句中用作主語(yǔ)的從句叫主語(yǔ)從句.
A 為了強(qiáng)調(diào)主語(yǔ)從句的內(nèi)容,可將從句置于句首
B 大部分主語(yǔ)從句都可以用it作形式主語(yǔ)

為了保持句子平衡,主語(yǔ)從句常用it作形式主語(yǔ),將主語(yǔ)從句后置.用it作形式主語(yǔ)的主語(yǔ)從句結(jié)構(gòu)有如下幾種：
1、It is + 名詞 + that從句
2、It is + 形容詞 + that從句
3、It + 動(dòng)詞 + that從句
4、It is + 過去分詞 + that從句
用形式主語(yǔ)it引導(dǎo)的主語(yǔ)從句相當(dāng)多,有些已形成固定的語(yǔ)法和譯法.常見的有：
It is said that... 據(jù)說……
It is reported that... 據(jù)報(bào)導(dǎo)……
It is well known that... 眾所周知……
It is announced that... 據(jù)宣布……
It is believed that... 人們相信……
It is thought that... 人們認(rèn)為……
It is understood that... 自不待言……
It must be pointed out that... 必須指出……
It must be admitted that... 必須承認(rèn)……
（二）賓語(yǔ)從句

賓語(yǔ)從句 The Object Clause,在復(fù)合句中作主句的賓語(yǔ),它屬于名詞性從句.它可以作主句謂語(yǔ)動(dòng)詞的賓語(yǔ),也可以作介詞的賓語(yǔ).賓語(yǔ)從句以從句的句式來決定連接詞.

賓語(yǔ)從句有四步曲
連接詞： （也叫引導(dǎo)詞）
語(yǔ)序： 從句的詞序用陳述語(yǔ)序（主+ 謂）
時(shí)態(tài)： 主句的時(shí)態(tài)如果是過去時(shí),從句的時(shí)態(tài)應(yīng)以過去時(shí)為基礎(chǔ)作相應(yīng)的變化.
人稱： 要根據(jù)句中的意義作相應(yīng)的變化

連接詞（引導(dǎo)詞）
從屬連詞 that ,if ,whether
連接代詞 who, whom, whose, which, what
連接副詞 when ,where ,how ,why
1.如果陳述句作從句,連接詞用that,在口語(yǔ)和非正式語(yǔ)體中?？墒÷詔hat .
2.特殊疑問句作從句,就用原來的特殊疑問詞
3.一般疑問句作從句,連詞用if或whether 在選擇疑問句只用whether,記住這一結(jié)構(gòu)：whether … or not .
（三）表語(yǔ)從句

表語(yǔ)從句放在連系動(dòng)詞之后,充當(dāng)復(fù)合句中的表語(yǔ).

A 可接表語(yǔ)從句的連系動(dòng)詞
可接表語(yǔ)從句的連系動(dòng)詞有be, look, seem, sound, appear等.
B as, as if / though引導(dǎo)的表語(yǔ)從句
C because, why引導(dǎo)的表語(yǔ)從句
what引導(dǎo)的主語(yǔ)從句表示結(jié)果或名詞reason作主語(yǔ)時(shí),后面的表語(yǔ)從句表示原因時(shí)要用that引導(dǎo),不宜用because.
D 使用虛擬語(yǔ)氣的表語(yǔ)從句
在表示建議、勸告、命令含義的名詞后的表語(yǔ)從句,謂語(yǔ)動(dòng)詞需用"should+動(dòng)詞原形"表示,should可省略.常見的詞有：advice, suggestion, order, proposal, plan, idea等.
（四）同位語(yǔ)從句

同位語(yǔ)從句用于對(duì)前面的名詞作進(jìn)一步解釋,說明名詞的具體內(nèi)容.同位語(yǔ)從句一般由that引導(dǎo),但也可以由whether以及連接代詞和連接副詞引導(dǎo).

A 同位語(yǔ)從句一般跟在名詞的后面
同位語(yǔ)從句一般跟在名詞fact, hope, idea, news, doubt, suggestion, information, opinion, decision, discovery, truth, promise, statement, problem, rule等后面.
B 使用虛擬語(yǔ)氣的同位語(yǔ)從句
在一些表示“建議、命令、要求”的名詞后的同位語(yǔ)從句中,謂語(yǔ)動(dòng)詞用"should + 動(dòng)詞原形",should可省略.