关系代词有:who, whom, whose, that, which, as。
I don't like the way (不用引导词.that, in which) he eyed me.
He is the man whowants to see you.
He is the man who I saw in the park yesterday.
He is the man(whom)I saw in the park yesterday.
whose 用来指人或物，(只能用作定语, 若指物，它还可以同of which互换)。
They rushed over to help the man whosecar had broken down.
Please pass me the book whosecover is green. (of which the cover/the cover of which)
They needed a plant whichdidn't need as much water as rice.
The farm (which)we visited yesterday is located in the suburb of Beijing.
I never met Julia again after that, whichwas a pity.
He can swim in the river, whichI cannot.
They are all questions to whichthere are no answers.
It's a question that (which)needs careful consideration.
Who is the man thatis reading a magazine under the tree?
The girl (that)we saw yesterday is Tom's sister.
All(that)she lacked was training.
This is the bestfilm thatI have ever seen.
They talked about the teachers and the schools thatthey had visited.
地点状语从句通常由where, wherever 引导。
WhereI live there are plenty of trees.
WhereverI am I will be thinking of you.
方式状语从句通常由as, (just) as…so…, as if, as though引导。
1) as, (just) as…so…引导的方式状语从句通常位于主句后，但在(just) as…so…结构中位于句首，这时as从句带有比喻的含义，意思是"正如…"，"就像"，多用于正式文体，例如:
Always do to the others asyou would be done by.
Aswater is to fish, so isair to man.
Just aswe sweep our rooms, sowe should sweep backward ideas from our minds.
2) as if, as though
They completely ignore these facts as if (as though)they never existed.
He looks as if (as though)he had been hit by lighting.
It looks as ifthe weather may pick up very soon.
He stared at me as ifseeing me for first time.
He cleared his throat as ifto say something.
比较:because, since, as和for
1) because语势最强，用来说明人所不知的原因，回答why提出的问题。当原因是显而易见的或已为人们所知，就用as或 since。
I didn't go, becauseI was afraid.
Since /Asthe weather is so bad, we have to delay our journey.
He is absent today, because / forhe is ill.
He must be ill, forhe is absent today.
表示目的状语的从句可以由that, so that, in order that, in case等词引导，例如:
You must speak louder so that /in order that you can be heard by all.
Better take more clothes in casethe weather is cold.
其规律由so与such的不同词性决定。such 是形容词，修饰名词或名词词组，so 是副词，只能修饰形容词或副词。 so 还可与表示数量的形容词many, few, much, little连用，形成固定搭配。
sofoolish, sucha fool
sonice a flower, sucha nice flower
somany / few flowers, suchnice flowers
somuch / little money, suchrapid progress
somany people, sucha lot of people
( so many 已成固定搭配，a lot of 虽相当于 many，但 a lot of 为名词性的，只能用such搭配。)
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
连接词主要有 if, unless, as/so long as, on condition that 等。.
unless = if not.
Let's go out for a walk unlessyou are too tired.
Ifyou are nottoo tired, let's go out for a walk.
注意:当有though, although时，后面的从句不能有but，但是 though 和yet可连用
Althoughit's raining, they are still working in the field.
3) even if, even though. 即使
We'll make a trip even thoughthe weather is bad.
4) whether…or- 不管……都
Whetheryou believe itornot, it is true.
5) "no matter +疑问词" 或"疑问词+后缀ever"
No matterwhat happened, he would not mind.
Whateverhappened, he would not mind.
替换:no matter what = whatever
no matter who = whoever
no matter when = whenever
no matter where = wherever
no matter which = whichever
no matter how = however
(错)No matter what you say is of no use now.
(对)Whateveryou say is of no use now.(无论你说什么都是无用的)
你现在说什么也没用了。(Whatever you say是主语从句)
(错)Prisoners have to eat no matter what they're given,
(对)Prisoners have to eat whateverthey're given. 囚犯们只能给什么吃什么。
比较while, when, as
1)as, when 引导短暂性动作的动词。
Just as / Just when / WhenI stopped my car, a man came up to me.
Whenyou have finished your work, you may have a rest.
Asthe day went on, the weather got worse.
I slept untilmidnight. 我一直睡到半夜时醒了。
Wait tillI call you. 等着我叫你。
(在肯定句中可用before代替 Let's get in the wheat beforethe sun sets.)
She didn't arrive until6 o'clock.
Don't get off the bus untilit has stopped.
Untilyou told me, I had heard nothing of what happened.
---Until whenare you staying? 你待到什么时候?
---Untilnext Monday. 待到下周一。
(1)Not until …在句首，主句用倒装。
Not untilthe early years of the 19th century did manknow what heat is.
Not untilI began to work did Irealize how much time I had wasted.
(2) It is not until… that…
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置于句首，句子必须用倒装结构:
Hardly / Scarcely had Igot home when it began to rain.
No sooner had Igot home than it began to rain.
在复合句中充当主语成分的句子叫做主语从句。常规主语从句，即句子在复合句中充当一个主语。主语从句的时态:不受主句的时态影响和限制。(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.小结:(1)引导主语从句连词有that,whether,who,what,whatever等(2)连词位于句首不能省略(3)主语从句大多数情况下视为第三人称单数，但也有例外，如例(9)
2)表示"是否"的 意义时用whether或if (当句中有or是只能用whether而不用if)
3)引导特殊疑问句意义的句子时用特殊疑问词who, whose, whom, which, what, when, where, 或how.
Everybody knows that money doesn't grow on trees.
Please go and find out when the train will arrive.
I am interested in what she is doing.
I don't suppose you're used to this diet.
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也可用来引导表语从句。
She seems as if she had done a great thing.
It is because you eat too much.
My suggestion is that we (should)go and help him.
Our only request is that this shouldbe settled as soon as possible.
·同位语从句一般跟在某些名词如answer(答案)，hope(希望)，fact(事实)，belief (信仰)，news(消息)，idea(主意;观念)，promise(承诺)，information(信息)，conclusion(结论)，order(命令)， suggestion(建议)，problem(问题)，thought (想法)等后面。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.
He hasn't made the decision whetherhe will go there.
I have small doubt whetherhe is suitable for the job.
I have no idea whathe is doing now.
It's a question howhe did it