连词的定义：
连词是连接字、短语、从句与句子的词，是虚词，因此它不能独立担任句子成分。连词主要分为两大类：并列连词和从属连词。并列连词用来连接并列关系的词、词组或分句。它包括：and，or，but，so，for，both…and，either…or，neither…nor，not only…but also。
从属连词用来引导从句，它包括： that， when， till， until， after， before， since，because，if，whether，though，although，so…that，so that，in order that，as soon as
并列连词用来连接具有并列关系的词，短语或句子。常见的并列连词有：
(1)表并列关系的and, both…and, not only…but also, neither…nor等。
(2)表选择关系的or, either…or等。
(3)表转折关系的but, while等。
(4)表因果关系的for, so等。
1并列连词
1 and：和，并且
I like basketball， football and table-tennis.
我喜欢篮球、足球和乒乓球。
1.基本用法
and表示“和”、“而且”的意思，用来连接对等关系的字和字，片语与片语，句子与句子。
He got up and put on his hat.
他站起来，戴上了帽子。
I went to the Summer Palace and he went to Bei Hai Park.
我去颐和园，他去北海公园。
注意
单词或词组如果是三个以上连接，一般在最后的单词或词组前加and。另外“and”在译成中文时不一定要翻译出“和”来。
2.特别用法：and在祈使句中的作用
句型：祈使句， and…=If you…， you'll…
Use your head，and you'll find a way.
动动脑筋，你就会想出办法来。
=If you use your head，you'll find a way.
如果你动动脑子，你就会想出办法。
Hurry up，and you'll catch the bus.
快点，你就会赶上公共汽车。
=If you hurry up，you'll catch the bus.
如果你快点，你就会赶上公共汽车。
2 or：或，或者，否则
Is Li Ming from Beijing or from Shanghai.
李明是北京人还是上海人呢?
1.基本用法
or表示“～或”的意思，使用于两者之中选择一个的时候。
Would you like coffee or tea?
你喜欢咖啡还是茶?
Tom or I am right.我或者汤姆是对的。
Li Ming or his classmates are cleaning the room.
李明或者是他的同班同学在打扫房间。
注意
“A or B”作主语时，谓语动词随or后面的词(B)而定，因此例子中的谓语动词服从I，用am。
2.特别用法
句型：祈使句， or…=If you don't…， you'll…
同and一样，or在祈使句中的用法，译成“请…，否则…”，有转折的意思。
Hurry up，or you'll miss the bus.
快点吧，否则你就会误了公共汽车。
=If you don't hurry up，you'll miss the bus.
如果你不快点，你就会误了这班车。
Study hard，or you'll fail in the exam.
好好学吧，否则你考试就会不及格。
=If you don't study hard，you'll fail in the exam.
如果你不努力学习，你考试就会不及格。
注意
or疑问句的读法or前面的部分用升调，后面的部分用降调。
3 but：但是，可是，而
He is old， but he looks very young.
他老了，但他看起来很年轻。
Li Li likes violin but doesn't like piano.
李莉喜欢小提琴，(但是)不喜欢钢琴。
(but 后面省略了主语Li Li，因为与前面的主语成分相同)
Mary likes violin， but Tom doesn't.
玛丽喜欢小提琴，而汤姆不喜欢。
(doesn't后面省略了like violin，因为与前面的成分相同)
He isn't a teacher but a doctor.
他不是(一个)老师，而是医生。
They came here not for money but for the life.
他们到这儿来，不是要钱，而是要命。
注意
but所连接的句子，句中如果某些成分与前面相同，则可以省略。
4 so， for
It began to rain，so we had to stay here.
开始下雨了，我们不得不呆在这儿了。
1.so：所以，因此，于是
My teacher asked me to go， so I went.
我们老师让我去，因此我就去了。
比较
so除了作连词外，也可以作副词。
I hope you can pass the exam.
我希望你能通过考试。
I hope so.我也希望。
Don't walk so fast.别走得太快。
2.for：因为
I soon went to sleep， for I was tired.
我很快就入睡了，因为我太累了。
The sun has risen，for the birds are singing.
太阳升起来了，小鸟在唱歌。
比较
for和be cause for也可译为“因为”，但是它没有什么因果关系，不像because那样，而for只是说明解释而已。
5 both…and：和，既……也……
He can play both the violin and the piano.
他既会拉小提琴，又会弹钢琴。
1.《both…and…》构成的词组作为主语时，谓语动词用复数。
Both Li Ming and Li Li are good students.
(Li Ming和Li Li都是人，所以两者对等)
李明和李莉都是好学生。
注意
在《both…and…》句型中，and连接的词或词组要对等。
2.《both…and》的否定句表示部分否定。
He can't play both the violin and the piano.
他会拉小提琴或者会弹钢琴。(不全会)
Both Li Ming and Li Li are not good students.
明和李莉不都是好学生。(其中一个是好学生)
6 either…or，neither…nor
I want to visit either Tianjing or Shanghai.
我想参观天津或者上海。
I like neither English nor Chinese.
中文和英文我全不喜欢。
1.either…or：或……或……;不是……就是……
a.《either…or…》构成的词组作为主语时，谓语动词随其邻近的词，即or后面的词而定。
Either you or he is right.
不是你，就是他是对的。
b.此句型的否定句是全否定。
Either you or he isn't right.你和他都不对。
I don't want to visit either Tianjing or
Shanghai.天津和上海我都不想参观。
2.neither…nor：既不……也不……
a.当此词组担任主语时，谓语动词的用法和either…or的用法一样，由nor后面的词而定。
Neither you nor I am right.你和我都不对。
b.此句型本身是全否定，因此不能再用否定式，即不能再加not。
(×)Neither You nor I am not right.
比较
both …and ,either…or ,neither …nor 这三个句型的相互关系如下：
1.肯定句：I like both A and B.我喜欢A和B。
I like both coffee and tea.
我喜欢咖啡和茶。(茶和咖啡我都喜欢)
2.否定句：I don't like both A and B. =I like either A or B.
我不喜欢A 或B。
I like either coffee or tea .
咖啡和茶，我喜欢一样儿。
=I don't like both coffee and tea .
3.I don't like either A or B .=I like neither A nor B.
A和B 我都不喜欢。
咖啡和茶，我都不喜欢。
I like neither coffee nor tea .
I don't like either coffee or tea .
7 not only… but also：不但……而且
(1)Not only you but also your father is coming.
不但你，而且你父亲也要来。
(2)Jane is not only beautiful but also kind.
珍妮不但漂亮，而且人非常好。
1.基本用法：《not only…but also》担任主语时，此句型的谓语动词随 but also后面的部分而定，参见上文例(1)。
另外not only…but also连接对等的词或词组;例(1)you(你)和 your father(你父亲)都是人。例(2)beautiful(美的)和kind(亲切、慈祥)都是形容词。
2.该句型可以和“as well as”互换，但注意汉语翻译。
Your father as well as you is coming.
不但你，而且你父亲也要来。
注意
as well as的句子谓语动词随它前面的词“Your father”而定，所以用is coming.
Jane is kind as well as beautiful.
珍妮不但漂亮，而且为人很好。
2 从属连词
常见的从属连词有：
(1)引导时间状语从句的after, before, when, while, as, until, till, since, as soon as等。(2)引导条件状语从句的if, unless等。
(3)引导原因状语从句的because, as, since等。
(4)引导目的状语从句的so that, in order that等。
(5)引导让步状语从句的though, although, even if等。
(6)引导结果状语从句的so that, so…that, such…that等。
(7)引导比较状语从句的than, as…as等。
(8)引导名词从句的that, if , whether等。
1 that
I think(that) he likes football.
我想他喜欢足球。
that引导名词性从句(主语从句、表语从句、宾语从句和同位语从句)和定语从句，本书只介绍宾语从句。
1.that在宾语从句、间接引语中可以省略，主句与从句时态一致。
I think(that) he is tired.我想他累了。
I thought(that) he was tired.
注意
要特别注意主句与从句时态的呼应。如果主句是过去时，从句一律改为过去的时态，详见第二十章宾语从句。
2.如果主句的动词是 think， believe…;如果主句的主语是第一人称，变为否定句时，要否定主句，译成中文时，则否定从句。
I believe you will leave here.
我相信，你会离开这儿的。
I don't believe you will leave here.
我相信，你不会离开这儿的。
必背!
I hope that～我希望～
I think that～我认为～
I say that～我说～
I know that～我知道～
I find that～我发现～
be afraid that～恐怕～
be sure that～确认～
be glad(happy) that～很高兴～
(以上的that都可以省略)
2 when，while，till，until，since…
When he arrives there he will call you.
他到达那儿以后，他会给你打电话。
when， while， till， until， since， after， before， as soon as等是连接时间状语从句的连词。在时间状语从句中要特别注意时态的搭配：当主句是将来时，从句要用一般现在时。
注意
while所引导的从句的谓语动词只能是延续性的，不能用点动词。(如begin，stop…)
When I arrived there， it was raining.
当我到那儿时，天正在下雨。
I entered the room while(when) Li Ming was talking with her.
我进屋时，李明正在和她谈话。
I didn't go to sleep until(till)I finished my homework.
直到我做完作业，我才上床睡觉。
We won't work until(till) our teacher teaches us how to do it.
老师教给我们如何做这工作之后，我们才会开始做。
He came to China after the war was over.
比较
连词连接从句不同，意思不同。
He had been in China before the war was over.
战争结束前，他已经在中国了。
=The war was over before he came to China.
=The war had been over before he came to China.
战争结束后，他来到中国。
I have learned more than two thousand English words since I began learning English two years ago.
自从两年前我开始学习英语以来，我已经学习了两千多个英语单词了。
注意
since引导的是一个过去时的句子，说明自当时以来到现在(自从两年前以来)，主句一般要用现在完成时。
As soon as I get enough money，I'll buy it.
我一得到足够的钱，就买它。
3 because：因为，连接原因状语从句
She didn't go there，because she was ill.
因为她病了，所以她没去那儿。
1.回答Why问句时，只能用because，不能用for或 as.
Why are you late?
你为什么迟到?
Because I met a traffic accident on my way here.
因为在我来这儿的路上，遇到了车祸。
2.汉语中，我们经常说因为……所以，但在英文中有了because，就不能再用so。
(×)Because he was tired， so he couldn't walk there.
因为他累了，所以他不能走到那儿了。
4 if，though (although)
If it doesn't rain，we'll go to the park.
如果不下雨，我们就去公园。
Though I was tired， I still worked hard.
虽然我很累，可是我仍然努力地工作。
1.if：如果(引导条件从句)
You can pass the exam if you study hard.
如果你努力学习，你会及格的。
2.though，although：虽然(引导让步状语从句)和原因状语从句一样，如果用了though，although (虽然)就不能再用but(但是)。
Although(Though) I live near the sea， I'm not a good swimmer.
=I live near the sea，but I'm not a good swimmer.
虽然我住在海边，可是我游泳并不好。
注意
注意时态一致，和时间状语从句一样。主句是将来时之时，从句要用一般现在时。
5 so…that：太……以致……
He is so old that he can't work. = He is too old to work.
他太老了，不能工作。
The box is so heavy that I can't lift it.
=The box is too heavy for me to lift.
箱子太沉了，我抬不起来。
The girl is so beautiful that everybody likes her.
这个小女孩太漂亮了，每个人都喜欢她。
注意
注意此句型与too…to的互换。
so…that在肯定句中不能转换成too…to…。
三 连词比较
I and 与or
1) 并列结构中，or通常用于否定句，and用于肯定句。
2) 但有时and 也可用于否定句。请注意其不同特点：
There is no air or water in the moon.
There is no air and no water on the moon.
在否定中并列结构用or 连接，但含有两个否定词的句子实际被看作是肯定结构，因此要用and。
典型例题
---I don't like chicken ___ fish.
---I don't like chicken, ___ I like fish very much.
A. and; and B. and; but C. or; but D. or;and
答案C。否定句中表并列用or, but 表转折。
判断改错：
(错) We will die without air and water.
(错) We can't live without air or water.
(对) We will die without air or water.
(对) We can't live without air and water.
3 )表示选择的并列结构
(1) or 意思为"否则"。
I must work hard, or I'll fail in the exam.
(2) either…or 意思为"或者……或者……"。注意谓语动词采用就近原则。
Either you or I am right.
判断改错：
(错) They sat down and talk about something.
(错) They started to dance and sang.
(错) I saw two men sitting behind and whisper there.
(对) They sat down and talked about something.
(对) They started to dance and sing.
(对)I saw two men sitting behind and whispering there.
解析：
第一句： and 连接两个并列的谓语，所以 talk 应改为 talked。
第二句：and 连接两个并列的动词不定式，第二个不定式往往省略to，因此sang 应改为 sing。
第三句：and 连接感观动词saw 后面的用作的宾补的两个并列分词结构，因此whisper应改为whispering。
注意：and 还可以和祈使句或名词词组连用表示条件。(or也有此用法)
Make up your mind, and you'll get the chance.
= If you make up your mind, you'll get the chance.
One more effort, and you'll succeed.
= If you make one more effort, you'll succeed.
II but表示转折，while表示对比。
Some people love cats, while others hate them.
典型例题
--- Would you like to come to dinner tonight?
--- I'd like to, ___ I'm too busy.
A. and B. so C. as D. but
答案D。but与前面形成转折，符合语意。而表并列的and，结果的so，原因的as都不符合句意。
III so, therefore
He hurt his leg, so he couldn't play in the game.
注意：
a. 两个并列连词不能连用，但therefore, then, yet.可以和并列连词连用。
You can watch TV, and or you can go to bed.
He hurt his leg, and so / and therefore he couldn't play in the game.
b. although… yet…，但although不与 but连用。
(错) Although he was weak, but he tried his best to do the work..
(对) Although he was weak, yet he tried his best to do the work.
IV 比较so和 such
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。
so + adj. such + a(n) + n.
so + adj. + a(n) + n. such + n. (pl.)
so + adj. + n. (pl.) such +n. (pl.)
so + adj. + n. [不可数] such +n. [不可数]
so foolish such a fool
so nice a flower such a nice flower
so many/ few flowers such nice flowers
so much/little money. such rapid progress
so many people such a 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。
so…that与such…that之间的转换既为 so与such之间的转换。
Eg :The MP3 cost me ________ money that I ccouldn't afford to buy it .
A .so much .B .such much C .so many
D . such many .(Key :A )
注意:too .... to .. ,so ..... that .... , such .... that .... , enough ..... to ...., 的互换.
so that to = in order to /that 的用法.
Eg A .He is too young to go to school.
B .He is ____ a young boy _____ he ____ go to school .
C .He is ____ young ____ he ____ go to school .
D .He isn't ______ _______ ______ go to school (Keys :B :such , that , can't C :so ,that ,can't .D : old ,enough to )
易错分析：
①关于not…until
He stayed there until it was very late.
句中，stay是可延续性动词，所以不用not。
He didn't leave until it was very late.
句中，leave是不可延续性动词，所以用not
②because, so;although, but
上面已经提到，because和so及although和but不连用。
例如:
Because he was late, he didn't catch the first bus.
一定不可以说
Because he was late, so he didn't catch the first bus.
③or还是and
祈使句+or+陈述句前后是对立的
祈使句+and+陈述句前后是统一的
(or或and后的陈述句，常用一般将来时)
Study hard, or you won't pass the exam.
Study hard, and you will pass the exam.
两句都可以转换成“If条件句+主句”形式，注意：要去掉or和and：
If you don't study hard, you won't pass the exam.
If you study hard, you will pass the exam.
④because, since, as, for表示原因时的区别
尽管because, for, since, as都表示原因，但是用法上有不同.
because通常表示说话人认为这种理由或者原因是听话人所不知道的.
如:
He didn't attend the meeting because he had too much work to do.
since表示的原因是人们已知的事实，常译作“既然”。
如：
Since he can't answer this question, you'd better ask someone else.
as表示原因与since差别不大，只是语气更弱,多译为“由于”
如：
As I haven't seen the film, I can't tell you what I think of it.
for表示因果关系时，只能放在主句之后，不能放在句首。而且经常是对主句补充说明理由或推断原因。
如：
It rained last night, for the ground is wet.
⑤ as, when, while
这三个连词都可引导时间状语从句，但用法有所不同。
1) 当某事正在进行的时候，又发生了另一件事。While, when, as 都可用来引导表示“背景”的时间状语从句。例如：
As/When/While I was walking down the street I noticed a police car.
2) 当两个长动作同时进行的时候，最常用的是while。例如：
While mother was cooking lunch, I was doing my homework.
3) 当两个动作都表示发展变化的情况时，最常用的是as。例如：
As children get older, they become more and more interested in things around them.
4) 当两个短动作同时发生时，或表示“一边…一边…”时，最常用as。例如：
Just as he caught the fly, he gave a loud cry.
She looked behind from time to time as she went
5) 当从句的动作先于主句的动作时，通常用when。例如：
When he finished his work, he took a short rest.
6) 当从句是瞬间动作，主句是延续性动作时，通常用when。例如：
When John arrived I was cooking lunch.
(6)if, whether
if和whether都可作“是否”讲，在引导宾与从句是一般可互换。例如：
I wonder whether (if) you still study in that school.
I don’t know whether (if) he likes that film.
1) 引导主语从句时。例如：
Whether he will come to the party is unknown.
2) 引导表语从句时。例如：
The question is whether I can pass the exam.
3) 在不定式前。例如：
I haven’t made up my mind whether to go there or not.
，我们将会及时处理。
