複合句分為並列複合句compound sentence（也稱並列句）和主從或從屬複合句complex sentence（也稱複雜句），並列複合句compound sentence是有並列連詞：and、or、but連線；從屬複合句complex sentence由一個主句（Principal Clause）和一個或一個以上的從句(Subordinate Clause)構成。用疑問詞作引導詞，主句是全句的主體，通常可以獨立存在；從句則是一個句子成分，不能獨立存在。從句不能單獨成句，但它也有主語部分和謂語部分，就像一個句子一樣。所不同在於，從句須由一個關聯詞（conjunction）引導。 根據引導從句功能不同，大致可分為：主語從句、表語從句、賓語從句、定語從句、狀語從句等。
基本介紹
複句分類,定語從句,狀語從句,名詞性從句,
複句分類
從屬複合句可分為：
(1).定語從句（The Attributive Clause）；
(2).狀語從句（The Adverbial Clause）；
(3).名詞性從句（The Noun Clause）；
定語從句
定語從句的定義
定語從句在句中作定語，用來修飾一個名詞、名詞詞組或者代詞。
先行詞和引導詞
被修飾的名詞、名詞詞組或代詞叫做先行詞；
關係代詞和關係副詞
如果要修飾方式，用that或in which引導，或者不用引導詞。
I don’t like the way (不用引導詞.that, in which) he eyed me.
我不喜歡他看我的那個樣子。
關係代詞
He is the man who wants to see you.
He is the man who I saw in the park yesterday.
關係代詞
He is the man（whom）I saw in the park yesterday.
（whom在從句中作賓語）
關係代詞
whose 用來指人或物，（只能用作定語, 若指物，它還可以同of which互換）。
They rushed over to help the man whose car had broken down.
Please pass me the book whose cover is green. （of which the cover/the cover of which）
關係代詞
which指物，在從句中作主語或賓語，作賓語時在非正式語體中可以省略。
They needed a plant which didn't need as much water as rice.
The farm (which)we visited yesterday is located in the suburb of Beijing.
關係代詞
當在which和that面前進行選擇的情況下，一般情況下要選which：
2. 修飾整個主句。
I never met Julia again after that, which was a pity.
3. 修飾謂語部分。
He can swim in the river, which I cannot.
4.介詞+ which
They are all questions to which there are no answers.
關係代詞
that多用來指物，有時也可以用來指人；在從句中作主語或賓語。指物的時候多用that，也可用which。
It’s a question that (which)needs careful consideration.
（指物，作主語。）
Who is the man that is reading a magazine under the tree?
（指人，作主語。）
The girl (that)we saw yesterday is Tom’s sister.
（指人，作賓語，可省略。）
關係代詞
在以下的情況中，只能用that作引導詞，而不能用which作引導詞。
All(that)she lacked was training.
2.先行詞被形容詞最高級修飾時
This is the best film that I have ever seen.
3.先行詞被序數詞和the last修飾時
4.先行詞中既有人又有物時
They talked about the teachers and the schools that they had visited.
5.主句是含有who或which的特殊疑問句，為了避免重複時
狀語從句
Where I live there are plenty of trees.
Wherever I am I will be thinking of you.
（1） as, (just) as…so…引導的方式狀語從句通常位於主句後，但在(just) as…so…結構中位於句首，這時as從句帶有比喻的含義，意思是"正如…"，"就像"，多用於正式文體，例如：
Always do to the others as you would be done by.
你希望人家怎樣待你，你就要怎樣待人。
As water is to fish, so is air to man.
我們離不開空氣，猶如魚兒離不開水。
Just as we sweep our rooms, so we should sweep backward ideas from our minds.
正如打掃房屋一樣，我們也要掃除我們頭腦中落後的東西。
（2） as if, as though
They completely ignore these facts as if (as though)they never existed.
他們完全忽略了這些事實，就仿佛它不存在似的。（與事實相反，謂語用虛擬語氣。）
He looks as if (as though)he had been hit by lighting.
他那樣子就像被雷擊了似的。（與事實相反，謂語用虛擬語氣。）
It looks as if the weather may pick up very soon.
看來天氣很快就會好起來。（實現的可能性較大，謂語用陳述語氣。）
He stared at me as if seeing me for first time.
他目不轉睛地看著我，就像第一次看見我似的。
He cleared his throat as if to say something.
他清了清嗓子，像要說什麼似的。
比較：because, since, as和for
（1） because語勢最強，用來說明人所不知的原因，回答why提出的問題。當原因是顯而易見的或已為人們所知，就用as或 since。
I didn't go, becauseI was afraid.
Since /As the weather is so bad, we have to delay our journey.
（2） 由because引導的從句如果放在句末，且前面有逗號，則可以用for來代替。但如果不是說明直接原因，而是多種情況加以推斷，就只能用for。
He is absent today, because / for he is ill.
He must be ill, for he is absent today.
You must speak louder so that /in order that you can be heard by all.
Better take more clothes in case the weather is cold.
結果狀語從句常由so… that 或 such…that引導，掌握這兩個句型，首先要了解so 和 such與其後的詞的搭配規律。
比較：so和 such
其規律由so與such的不同詞性決定。such 是形容詞，修飾名詞或名詞詞組，so 是副詞，只能修飾形容詞或副詞。 so 還可與表示數量的形容詞many, few, much, little連用，形成固定搭配。
sofoolish, such a fool
sonice a flower, such a nice flower
somany / few flowers, such nice flowers
somuch / little money, such rapid progress
somany people, such a lot of people
（ so many 已成固定搭配，a lot of 雖相當於 many，但 a lot of 為名詞性的，只能用such搭配。）
so…that與such…that之間的轉換既為 so與such之間的轉換。
The boy is so young that he can't go to school.
He is such a young boy that he can't go to school
unless = if not.
Let's go out for a walk unless you are too tired.
If you are not too tired, let's go out for a walk.
連線時間狀語從句的連線詞有：when, before, after, while, as soon as, until, since...... 這裡要注意一點的 是，如果主句是一般將來時，從句只能用一般現在時表示將來意義。
though, although
注意：當有though, although時，後面的從句不能有but，但是 though 和yet可連用
Although it's raining, they are still working in the field.
(3) even if, even though. 即使
We'll make a trip even though the weather is bad.
(4) whether…or- 不管……都
Whether you believe itornot, it is true.
(5) "no matter +疑問詞" 或"疑問詞+後綴ever"
No matter what happened, he would not mind.
Whatever happened, he would not mind.
替換：no matter what = whatever
no matter who = whoever
no matter when = whenever
no matter where = wherever
no matter which = whichever
no matter how = however
（錯）No matter what you say is of no use now.
（對）Whateveryou say is of no use now.（無論你說什麼都是無用的）
你現在說什麼也沒用了。(Whatever you say是主語從句)
（錯）Prisoners have to eat no matter what they're given,
（對）Prisoners have to eat whateverthey're given. 囚犯們只能給什麼吃什麼。
比較while, when, as
（1）as, when 引導短暫性動作的動詞。
Just as / Just when / WhenI stopped my car, a man came up to me.
Whenyou have finished your work, you may have a rest.
（3）從句表示"隨時間推移"連詞能用as，不用when 或while。
Asthe day went on, the weather got worse.
日子一天天過去，天氣越變越壞。
比較until和till
這兩個連詞意義相同。肯定形式表示的意思是"做某事直至某時"，動詞必須是延續性的。否定形式表達的意思是"直至某時才做某事"。動詞為延續性或非延續性都可 以。 正確使用這兩個連詞的關鍵之一就在於判斷句中的動詞該用肯定式還是否定式。
肯定句：
I slept untilmidnight. 我一直睡到半夜時醒了。
Wait tillI call you. 等著我叫你。
（在肯定句中可用before代替 Let's get in the wheat beforethe sun sets.）
否定句：
She didn't arrive until6 o'clock.
Don't get off the bus untilit has stopped.
(1)Until可用於句首，而till通常不用於句首。
Untilyou told me, I had heard nothing of what happened.
直到你告訴我以前，出了什麼事我一點也不知道。
(2)Until when疑問句中，until要放在句首。
---Until whenare you staying? 你待到什麼時候？
---Untilnext Monday. 待到下周一。
注意：否定句可用另外兩種句式表示。
(1)Not until …在句首，主句用倒裝。
Not untilthe early years of the 19th century did manknow what heat is.
直到19 世紀初，人類才知道熱能是什麼。
Not untilI began to work did Irealize how much time I had wasted.
直到我開始工作，我才認識到了我已蹉跎了幾多歲月。
(2) It is not until… that…
10 表示"一…就…"的結構
hardly/scarcely…when/before, no sooner…than 和as soon as都可以表示"一…就…"的意思，例：
I had hardly / scarcelygot home whenit began to rain.
I had no soonergot home thanit began to rain.
As soon asI got home, it began to rain.
注意：如果hardly, scarcely 或no sooner置於句首，句子必須用倒裝結構：
Hardly / Scarcely had Igot home when it began to rain.
No sooner had Igot home than it began to rain.
名詞性從句
在複合句中充當主語成分的句子叫做主語從句。常規主語從句，即句子在複合句中充當一個主語。主語從句的時態：不受主句的時態影響和限制。（1）That he finished writing the composition in such a short time surprised us all.（2）Whether we will go for an outing tomorrow remains unknown.（3）Who will be our monitor hasn't been decided yet.（4）Whom we must study for is a question of great importance.（5）What caused the accident remains unknown.（6）Whatever you did is right.（7）Who the watch belongs to is unknown.（8）What we need is time.（9）What we need are good doctors.小結:（1）引導主語從句連詞有that,whether,who,what,whatever等（2）連詞位於句首不能省略（3）主語從句大多數情況下視為第三人稱單數，但也有例外，如例（9）
注意：當what引導的名詞性分句作主語時，主謂一致問題極為複雜。著名學者周海中教授在論文《關於what-分句作主語的主謂一致問題》中就這一問題做了深入研究，並給出了10種的主謂一致關係。這些一致關係值得英語學習者和使用者特別注意。
賓語從句的引導詞有三種情況:
（1）引導陳述意義的 句子用that，無實際意義，口語中可以省略。
（2）表示“是否”的 意義時用whether或if （當句中有or是只能用whether而不用if）
賓語從句的時態:
·賓語從句：及物動詞的賓語
Everybody knows that money doesn't grow on trees.
·賓語從句：短語動詞的賓語
Please go and find out when the train will arrive.
·賓語從句：介詞的賓語
I am interested in what she is doing.
·賓語從句：否定的轉移
I don't suppose you're used to this diet.
我想你不習慣這種飲食。
·表語從句
What the police want to know is when you entered the room.
This is what we should do.
That's why I want you to work there.
as if, as though, because也可用來引導表語從句。
She seems as if she had done a great thing.
It is because you eat too much.
主語是idea, notion, proposal, suggestion, request等名詞時,作表語從句的動詞為原形動詞或should+原形動詞。
My suggestion is that we (should)go and help him.
Our only request is that this shouldbe settled as soon as possible.
·同位語從句一般跟在某些名詞如answer(答案)，hope(希望)，fact(事實)，belief (信仰)，news(訊息)，idea(主意；觀念)，promise(承諾)，information(信息)，conclusion(結論)，order(命令)， suggestion(建議)，problem(問題)，thought (想法)等後面。例如：
I had no idea thatyou were here.
She told us her hope thatshe would become a pianist.
He made a promise thathe would never come late.
·同位語從句：whether
He hasn’t made the decision whetherhe will go there.
