I 定語從句
1.先行詞為all， anything， something， nothing， everything， much， little， none等不定代詞時，關係代詞一般只用that，不用which。在大多數情況下that可以省略.
Please tell me everything (that) you know about the matter.
That’s all (that) we can do at the moment.
引出的限制性定語從句
在such … as的結構中as可作關係代詞，引出限制性定語從句。有時和same連用，在從句中可作主語、賓語或表語等。
Such people as were recommended by him were reliable.
I’ve never seen such a talented young man as he is.
I have the same trouble as you (have)。
引出的非限制性定語從句
as可作關係代詞引出非限制性定語從句，代替整個主句，通常譯為“(正)如…一樣”，“(正)象…一樣”等。as引導的從句一般用逗號與主句隔開，可以位於主句的前面、中間或後面.
I live a long way from work， as you know.
She did not， as her friend had feared， break down.
As is generally accepted， economic growth is determined by the smooth development of production.
4.分隔式定語從句
定語從句一般緊跟在先行詞之後，但有時會被其他句子成分與先行詞隔開，從而構成分隔式定語從句。
The days are gone when power politics worked.
A new teacher will come tomorrow who will teach you French.
5.介詞+關係代詞(which/whom等)引出的定語從句
如果關係代詞(which/whom等)在定語從句中作介詞的賓語，那麼這個介詞可以提到從句前，構成“介詞+關係代詞(which/whom等)+定語從句”。在這種結構中關係代詞不可以用that。
This is a subject about which we might argue for a long while.
The four travelers with whom I shared the room were pleasant people.
6.關係代詞在限制性定語從句中常可以省略，一般有以下幾種情況：
1) 關係代詞在從句中作直接賓語時，在大多數情況下可以省略。
This is something (that) you must always keep in mind.
The man (whom) you just met is our manager.
關係代詞作介詞賓語時，介詞位於句尾時關係代詞可以省略;介詞位於關係代詞之前時則關係代詞不能省略。
This is the room (which) Churchill was born in.
This is the room in which Churchill was born.(which不可省略)
2) 關係代詞作主語時一般不能省略，但如果關係代詞在由there … be存在句構成的定語從句中作主語時常可省略。
This is the only book (that) there is on this subject.
The old professor made full use of the time (that) there was left to him to continue his research.
3) 在way後面的定語從句中in which或that通常省略。
That’s the way (that/in which) I look at it.
I don’t like the way (that/in which) you laugh at her.
7.非限制性定語從句
非限制性定語從句修飾先行詞或整個主句，起補充說明的作用，如果省略掉，原句句意仍保持完整。非限制性定語從句要用逗號與主句隔開，其引導詞不能用that。非限制性定語從句屬於正式語體。經常考到的非限制性定語從句有以下三種。
1)由which、as引導的非限制性定語從句。which、as代表整個主句。
He said that he had never seen her before， which was not true.
China is still a developing country， which is known to all of us.
2)由 “介詞+關係代詞”引導的非限制性定語從句。
He sent her a letter， in which he said that he was sorry for what he had done to her.
He failed to pass the exam， because of which his parents scolded him.
4) 由 “數詞、代詞或名詞+of +關係代詞”引導的非限制性定語從句。
He had three sons， one of whom was my son’s classmate.
There are about twenty students in this course， most of whom are freshmen.
They are two different words， the spellings of which are easily confused.
Ⅱ 狀語從句
狀語從句中以下四種從句考得較多，這裡給予簡單介紹。
1) 時間狀語從句
時間狀語從句主要由以下連詞引導：when， whenever， as， while， since， until， till， before， after， as soon as， once， hardly (scarcely) … when， no sooner … than。
I will discuss the matter with you when we meet tomorrow.
He didn’t go to sleep until he finished doing his homework.
You have changed a lot since we met last time.
時間狀語從句還可由某些可充當連詞的名詞(the moment， the instant， every time，等)和副詞(instantly， directly等)引導：
I will tell you the news the instant I know.
Directly the teacher came in everyone was quiet.
Note：
①before除了可表示 “在…之前”外，還可用來強調主句所表達的時間、距離很長或花費的力量相比較大，可譯為“…才”。(“not … before” 可用來強調主句所表達的'時間、距離很短或花費的力量相比較小，可譯為“…就”)。
It was a long time before I got to sleep again.
They had not been married a month before they quarreled.
②如果位於when引導的分句之前的主句使用過去進行時、過去完成時或“was/were about to， was/were on the point of”等結構時，when表示突然發生某事，可譯為“正在…突然”或“剛…就”等。這時，不能夠用as或while來代替when。
I was walking on the street when I ran into my old friend John.
She had just fallen asleep when the telephone rang.
We were about to leave when it began to rain.
2) 條件狀語從句
條件狀語從句主要由以下連詞引導：if， unless， providing/provided (that)， suppose/supposing (that)， on condition (that)， as/so long as， in case等。
So long as you work hard， you will surely achieve good results in examinations.
I shall return next Thursday unless something unexpected happens.
I will go provided that you go with me.
Please give this letter to John in case he comes.
3) 讓步狀語從句
讓步狀語從句主要由以下連詞引導：though， although， even if， even though， whatever， however， whoever， wherever， no matter how/ what/ where/ when等。以下介紹幾種較特殊的讓步狀語從句。
(1)while引導的讓步狀語從句多放在句首，while相當於although，表示“儘管”，“雖然”。
While I admit I did it， I didn’t intend to.
While I understand what you say， I can’t agree with you.
(2)短語“even now/then/so”相當於“though it is/was true”，表示“儘管如此”，“儘管這樣”。
The fire was out， but even so， the smell of smoke was strong.
I’ve tried my best， but even now/then she is not satisfied.
(3) as引導的讓步狀語從句要倒裝。
Child as he was， he could speak four languages.
Hard as she tried， she failed to get the job.
4) 比較狀語從句
比較狀語從句主要由以下連詞引導：(not) as … as， (not) the same as， (not) such … as， not so … as， than， the + 比較級…， the +比較級…等。
We have had a lot more rainfall this year than we had last year.
She can speak English as fluently as her teacher (can)。
Ⅲ 賓語從句
1) 及物動詞後的賓語從句
有些動詞的賓語從句前還可有一個間接賓語。
I remember that we have learned this word before.
I don’t understand what you have said.
She asked the teacher how she could learn English well.
2) 介詞的賓語從句
It depends on whether you want to do it or not
There is disagreement among economists about what money is and how money is measured.
Note： 在介詞in後面跟that引導的賓語從句中，in that可看成是一個固定的搭配，表示“因為”或“在…方面”。
The evidence is invalid in that it was obtained through illegal means.
A turtle differs from all other reptiles in that it has its body encased in a protective shell of its own.
