连词是虚词，不能在句中单独担任成分，只起连接作用。按其用法，连词可分为两大类：并列连词和从属连词。
1并列连词
连接具有并列关系的词、短语或句子。
⒈ 并列关系：and，not only…but also…，both…and…，neither…nor…
如：I used to live in Paris and London.
Both Jane and Jim are interested in fishing.
The weather here is neither too cold nor too hot.
She is not only kind but also honest.
⒉ 转折关系：but，yet，while（然而），when（然而，偏偏）
如：The car is very old but it runs very fast.
The problem was a little hard,yet I was able to work it out.
The winter in Beijing is very cold while that of Kunming is warm.
Why did you borrow the book when you had one?
⒊ 选择关系：or，not…but…，either…or…
如：Would you like to live or would you like to stay?
He is not a teacher but a writer.
You can come either on Saturday or on Sunday.
⒋ 因果关系：for
如：It must have rained last night,for the ground is wet now.
The leaves of the trees are falling. for already autumn.
5. 区别
① and和or
⑴ 并列结构中，or通常用于否定句，and 用于肯定句。
⑵ 但有时and 也可用于否定句。请注意其不同特点：
如：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。
判断改错：
（错)We will die without air and water.
（错）We cait live without air or water.
（对）We will die without air or water.
（对)We cant live without air and water.
② 表示选择的并列结构
⑴ or意思为“否则"。
I must work hard,or I will fail in the exam.
⑵ 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.
③ 表示转折或对比
⑴ but表示转折，while表示对比。
Some people love cats,while others hate them.
⑵ not…but…意思为“不是……而是……"not和but后面的用词要遵循一致原则。
They were not the bones of an animal,but(the bones) of a human being.
③ 表原因关系
⑴ for是并列连词，不能置于含两个并列分句的句子的句首，只能将其放在两个分句中间。
判断改错：
（错）For he is ill,he is absent today.
（对）He is absent today,for he is ill.
④ so,therefore
如：He hurt his leg, so he coudn'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.
b.although，yet 但although不能与but连用。
⑤ 注意：
not only，but also 关联两个分句时，一个分句因有否定词not而必须倒装。
如：Not only does he like reading stories,but also he can even write some.
neither…nor… 意思为“既不……也不……“谓语动词采用就近原则，与nor后的词保持一致。
⑥ 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。
⑴ 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。
⑵ so，that与such，that之间的转换即为so与such之间的转换。
2
从属连词
指在复合句中引导从句的连结词。
⒈ 常见的从属连词有：
引导时间状语从句的：after，before，when，as，while，since，until，till，as soon as
引导原因状语从句的：because，since，as
引导让步状语从句的：although，though，no matter（无论），even if (though)
引导条件状语从句的：if，unless，once，as (so) long as
引导结果状语从句的：so，so that，so…that…，such…that…
引导目的状语从句的：so，so that…，in order that…
引导比较状语从句的：as…as，not so (as)，as，than
引导方式状语从句的：as，as if…，as though
引导地点状语从句的：where，wherever
引导名词性从句（主语，宾语、表语或同位语从句）的连词主要有：that，whether，if三个。其中that和whether间或还可以引起同位从句和状语从句。
⒉ 某些用法比较特殊的从属连词用法区别
① 当while,when,as引导时间状语从句时的区别：
⑴ while引导的状语从句中动词必须是延续性。谓语动词多为进行时，或状态动词的一般时。while的这些用法可用when代替，等于“at the time that",“during the time that”
如：Please keep quiet while(when)others are studying.
⑵ when除可指一段时间外，还可用来指一点时间，等于“at the time；when引出的时间状语从句中的谓语动词可以是终止性的，也可以是延续性的。因此主句和从句的谓语可以是一般时，进行时，或完成时。
如：When I went into the lab,the teacher was doing an experiment.（不能用while)
He often makes mistakes when he is speaking English （then 可换成while)
⑶ as 常可与when，while通用，但强调“一边、一边”。
如：As(when/while) I was walking down the street, I noticed a police car in front of number 37.
⑷ when 引导的状语从句中的主语与主句主语一致，主、谓是“主语 系动词”结构时，这时主语和系动词可以省略。
如：When (he was)young. he worked for a rich man.
She'll be here to give you help when (if it is)necessary.
⑸when有时代替if，引导条件句，意为“如果”“假如”。
如：I'll come when (if）I'm free.
② before作连词一般表示时间，意为“在.…之前”，但有些句子中这样译就显得别扭。
试看以下句子的翻译：He almost knocked me down before he saw.他且乎把我撞倒才看见我；
Before I could get in a word he had measure.没来得及插话，他已经给我量好了尺寸。
③ till,until作为介词式从属连词，只用于时间，引导时间状语短语或状语从句，用于否定句时，结构为not…until(till)主句谓语动词延续与非延续皆可，意为“直到……才……”。用于肯定句时，只与延续性动词连用，表示“到……为止”。
如：They played volleyball until(till)it got dark.
They didn't talk(延续）until(till) the interpreter（译员）came.
He didn't go to bed（非延续）until(till) the his father came back
但是，until可以放在句首，till则不行。
如：Until the last minute of the match we kept on playing.
Not until he finished his work did he go home.（倒装）
④ because,since,as引导原因状语时注意使用上的区别：
⑴ 如果原因构成句子的最主要部分，一般用because 因此because引导的从句往往放在句末。用why提问的句子，一定用because 回答。
如：He had to stay at home yesterday because he was ill.
⑵ 如原因已为人们所知，或不如句子的其他部分重要，就用as，或 since。since比as更正式些。as和since引导的从句一般放在句子的开头。
如：As you are tired,you had better rest/Since everyone is here,now let's begin.
⑤ although和though 引导让步状语从句往往用法一样，但注意以下区别：
⑴ although 用于各种文体，而though则多用于非正式的口语或书面语中。注意由 although,though 引导的从句后，主句不能用but，但可用副词yet，still。
如：Although/Though it rained all the morming, they still went on work或yet they went on working.
⑵ though 常与even连用，even though表示强调，意为“即使”，但不能说even although。
如：Even though he didn't understand a word,I dept smiling.
⑶ though可用作副词，意为“然而”，常用逗号与句子分开。lthough 则不能这样使用，它只作连词。
如：It was a quiet party,I had a good time though.
⑥ once作副词译“曾经”，作为连词译“一旦”，引导条件状语从句。相当于f的加强形式。
如：I don't believe he was once a thief.（once这是副词）
Once Aristotle（亚里士多德） had made up his mind that heavy objects always fell faster than light objects,he taugh as a truth to his students.(once连词）
⑦ umless引导条件状语从句等于if…not…
如：He'll accept the job unless the salary is too low.
⑧ 在用as if引导的方式状语从句及表语从句中，根据情况要使用虚拟语气。
例如：He talks as if he knew all about.但有时也可用直陈语气。
It looks as if it is going to rain.
⑨ whether，if引导从句的用法区别：
⑴ 引导主语从句、表语从句或同位语从句时，用whether，不用if。
如：whether they will go to the Great Wall is not known.
The question is whether we can finish the task on time.
The question whether we will take part in the physics contest has not been decided.
⑵ whether 可接不定式，而if则不可。
如：I haven't decided whether to leave or not.
⑶ whether 可作介词的宾语或置于句首表示强调，而if则不可。
如：Everything depends on whether we have enough money.
Whether he will come,I am not sure.
⑷ whether 和if 均可引导宾语从句，whether引导的宾语从句一般都是肯定句，if引导的宾语从句可以是肯定的，也可以是否定的（此时不能用whether）。
如：Could you tell us whether/if it rains in winter in Australia?
I wonder if it doesn't rain.
⑸ 引导宾语从句的whether 和if常可与or not连用。连用时要注意or not的位置，它一般与whether、if分开使用，有时它可与whether 合起来使用，但不能与if合起来使用。
如：I don't know whether/ if they will come or not.
I don't know whether or not they will come.
⑹ if可用来引导条件状语从句，译“如果”，whether则不行。
例如：If you work hard,you are sure to succeed.
⑩ as作从属连词可引导多种状语从句。
⑴ as 引导时间状语从句，意为“当…时”。
例如：As (he was)a young man,he was a storekeeper and later a postmaster./He sang as he worked.
⑵ as 引导方式状语从句，意为“像……一样”。
例如：We must do as the Party teaches us.
⑶ as引导原因状语从句，意为“由于”。
例如：As you are tired,you had better rest.
⑷ as i引导让步状语从句。意为“虽然”“尽管”。
例如：Child as he is,he can do it well.(=Although he is a child， he can do it well.)另外，as做为关系代词还可以引导定语从句，如：I have the same book as you.
⑪ while 的考察点
⑴ 考查表示时间的用法，其意为“当，的时候”。
如：We must strike while the iron is hot.截们要趁热打铁。
Stand still while I take your photograph.我给你拍照时站着不要动。
Have we got enough books to read while we are on holiday?假期里我们有足够的书看吗?
⑵ 考查表示让步的用法，其意为“尽管”“虽然”。如：while the work was difficult,it was interesting.虽然工作有难度，但很有趣。
while I understand what you say,I can't agree with you.虽然我理解你的意思，但我还是不同意。
⑶ 考查表示对比的用法，其意为“而”“但”。
如：Some people waste food while others haven't enough.一些人糟踏食物而另一些人却食不果腹。
I went swimming while the others played tennis. 我去游泳，而其余的人则去打网球了。
注：这样用时，while引出的句子通常位于末，但有时也可位于句首。
如：while most children learn to read easily,some need extra help. 大多数儿童学会阅读很容易，有一些儿童却需要特别帮助。
while Deauville is a holiday resort,Trouville is more of a working town. 特维尔是个度假胜地，而特鲁维尔更多的却是个工业城市。
考查其省略用法，即主句与从句主语相同，且从句谓语动词含有动词be时，通常可省略从句主语和动词be。
如：while (she was)in prison she wrote her first novel.她在狱中写出了第一部小说。
He had strayed from home while still a boy.他小时候就离开家到处流浪了。
He fell asleep while (he was)doing his homework.他做着做着功课就睡着了。
I was only listening to the radio with half an ear,while I was)preparing some food.我正在做吃的东西，没太留心听收音机。
III.高考英语短文改错及语法填空考点分析及训练·连词
考点规律分析:短文改错对并列连词的考查主要涉及and, but, or, so 等几个表示并列、转折、选择、因果等关系的词语。严格说来，这类错误主要属于行文逻辑的错误。语法填空主要涉及连词的选择。
连词单句改错之真题训练：
1. We tried to fix it and there was nothing we could do.
2. I told Mother, Father, Sister, all my friends here what a great time I had.
3.It is a very important exam but I can't afford to fail it.
4. She was smiling but nodding at me.
5. It looks as if my parents treat me as a visitor and a guest.
6. The food was expensive and the service was good.
7. I'm the captain of our school team so with my fellow players we've won several games.
8.My grandma was the best cook in the world but could make the most delicious dishes.
9.So once you've started collecting seriously, you…
10. Clever as she is, but she works very hard.
11. I teach them, play with them, but watch them growing up.
连词单句改错之模拟训练：
1. Do you want a bath at once, and shall I have mine first?
2.Are you going to clean your car before and after supper?
3. Hurry up, and you'll be late for school.
4. She never said she was rich, and she was.
5. Mr Smith worked very hard so without any success.
6. Everyone asked me to go, but I went.
连词单句改错之提升训练：
1. It didn't matter that I would win the match or not.
2. That he is looking for is a dictionary.
3. Many people can quickly get help from a doctor since they are ill.
4. If you can pass the test is up to you.
5. If we will hold the party in the open air depends on the weather.
6. I live in Beijing, where has a long history.
7. We still don't know if or not they have arrived at Shanghai.
8. It is the tallest tower which can be seen far away.
9. The person about who we just talked is my maths teacher.
10. Yesterday we were having our dinner while the telephone rang.
11. But, there are still some people have not enough to feed on.
12. It is said, he has left for Germany.
13. I doubt that he is a spy.
14. I don't doubt whether you have told the truth.
15. He has no money and he has much knowledge.
参考答案及解析
连词单句改错之真题训练：
1.and 改为 but，因此处语意转折
2.all 前加 and，表示并列关系
3.but 改为 and / so，此处表因果关系，并非转折关系
4.but 改为 and，因此处并无转折之意
5.and 改为 or，a visitor 和 a guest 应是选择关系，意思是"好像我的父母亲把我当作一个来访者或一个客人"
6.and 改为 but，此处意义发生转折
7.so 改为 and，表并列关系
8.but 改为and，此处表示并列，而不是转折
9.So 改为 But，因为前后是转折关系
10.去掉but，因前面已有引导让步状语从句的连词 as(=though 虽然)，千万不要受汉语句式"虽然……但是……"的影响，而重复用连词
11.but 改为and，因为 teach / play 与 watch 是并列关系，而不是转折关系
连词单句改错之模拟训练：
【参考答案】
1. and 改为 or，or 在此表选择。
2. and 改为 or，or 在此表选择。
3. and 改为 or，or 在此表示"要不然"、"否则"。
4. and 改为 but，but 在此表示转折。句中的 she was 为 she was rich 之省略。
5. so 改为 but，此处语意转折。
6. but 改为 so，so 在此表示因果关系。
连词单句改错之提升训练：
【答案与解析】
1. that 改为whether。
2. That 改为What。主语从句缺少宾语，应用what引导。
3. since 改为when或if。因为后面是一个条件或时间状语从句。
4. If 改为Whether。主语从句不能用If引导。
5. If改为Whether。主语从句要用whether引导。
6. where 改为which。定语从句缺少主语。
7. if 改为whether。whether or not为固定用法。
8. which 改为that。定语从句的先行词tower被最高级tallest修饰。
9. who 改为whom。介词后关系代词指人时只能用whom。
10. while 改为when。when作并列连词，表示"这时候"，不能用while代替。
11. But改为However。注意后面的逗号。此处只能用连接副词，不能用连词。
12. It改为As。这是一个由as引导的定语从句。不要与It is said that…主语从句混淆了。
13. that 改为 whether。如动词doubt为肯定式，后面的宾语从句用 whether引导。
14. whether 改为 that。如 动词doubt为否定式，后面的宾语从句用 that引导。
15. and改为but。表转折关系。
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