概述
连词是一种虚词，用于连接单词、短语、从句或句子，在句子中不单独用作句子成分。连词按其性质可分为并列连词和从属连词。并列连词用于连接并列的单词、短语、从句或句子，如and, but, _or_ , for 等；从属连词主要引出名词性从句(主语从句、宾语从句、表语从句等)和状语从句(时间状语从句、条件状语从句、目的状语从句等)，引出名词性从句的连词如that, whether等，引出状语从句的连词如when, because, since, if 等。
连词用法和总结 - 并列连词
Part One: 表示转折关系的并列连词。
主要有 but(但是), yet(可是), while(而，却)等。如：
- I would have written before but I have been ill. 我本该早写信的，但我生病了。
- I have failed, yet I shall try again. 我失败了，但我还要尝试。
- You like tennis, while** I’d rather read. 你爱打网球，但我爱看书
- Someone borrowed my pen, but I don’t remember who. 有人借了我的钢笔，但我不记得是谁了。
- He said he was our friend, yet he wouldn’t help us. 他说他是我们的朋友，但却不肯帮助我们。
but 的用法
1. 连接词或短语
- It was a sunny but not very warm day. 那一天天气晴朗，却不太暖和。
- He drives not carefully but slowly. 他开车不是很小心，而是开得很慢。
2. 连接句子
- This isn’t a good one but it will answer. 这不太好，但可以将就用。
- He looks honest, but actually he’s a rogue. 他看起来很老实，实际他是一个坏蛋。
- She has had no answer to him but he gave no answer. 我向他说了早上好，但他没有回应。
- The ice remained, but there was no water underneath. 冰还在，但下面却没有水。
- Mrs. Brown was about to begin, but Jennie spoke first. 布朗夫人正要开始讲话，珍妮先讲了。
- At first he was a little shy, but now he acts more natural.
开始时他有些腼腆但现在他表现得很自然了。 - There was a little trouble at first, but things were soon quiet. 起初有点小麻烦后来情况就平静了。
3. 用于句首
- but that question doesn’t arise. 但没发生那个问题。
- but in secret she was delighted. 但她暗中感到高兴。
- but what else can we do? 我们还能做什么?
- but in the end he gave in. 但最后他还是让步了。
- but there’s one thing we are agreed on. 但有一点大家的意见是一致的。
4. 用于道歉的表达之后
- Sorry, but we’re behind schedule. 抱歉，我们落在计划后了。
- I’m frightfully sorry, but I can’t see you today. 太对不起了，我今天不能见你。
- Excuse me, but I don’t think that’s quite true. 很抱歉，我认为这与事实略有出入。
5. 用于not…but…，表示“不是……而是……”
- Not you but I am to blame. 不是你的错而是我的错。
6. 用在某些否定语后，表示“只……”
- He eats nothing but hamburgers. 他只吃汉堡包。
- She knows no one but you. 她只认识你。
- You have nobody but yourself to blame. 只能怪你自己。
- No one but me saw her. 只有我看见他
7. 用于next (last) but one 中，表示“隔壁再过去”“倒数第……”
- He lives in the next house but one. 他住在隔壁再过去一家。
- He was the last but one to arrive. 他是倒数第二个到的。
8. can’t help but 不由得不……
- You can’t help but respect them.
你不由得不尊敬他们。 - When they gave him a ticket to the game, he couldn’t help but go.
他们给了他一张看球赛的票，他不由得不去。 I can’t help but wonder what I should do next.
我不由得不想知道下一步该怎么办。_注意_ 不要按汉语意思将“虽然…但是…”直译为although…but…：
_误_ ：Though we are poor, but we are happy. (去掉though或but中任一个)
9. but 与 however的用法异同 两者均可表示转折或对比，意为“但是”、“可是”、“然而”等，但有区别：
表示转折时，but 是连词。如：
- He is young but very experienced. 他虽年轻，但经验很丰富。
- He has three daughters but no sons. 他有3 个女儿，但没有儿子。
- He likes sports, but his wife likes music. 他喜欢运动，而他妻子则喜欢音乐。
however 表示“然而”、“可是”时，有的词书认为它是连词，有的词书认为它是副词。之所以将其视为副词，也许是因为像许多副词一样不仅能位于句首，而且能位于句中(注意前后使用逗号)，甚至句末(注意其前也用逗号)。如：
- Later, however, he changed his mind. 可是他后来改变了主意。
- He hasn’t arrived. He may, however, come later. 他还没有到，不过他等会儿可能会来。
- He said that it was _so_ ; he was mistaken, however. 他说情况如此，可是他错了。
_注意_：以上各例中的 however 不能换成 but，但可用 but 来改写。如：
- He said that it was _so_ , but he was mistaken. 他说情况如此，可他错了。
当连接两个句子时，其前通常应用分号，或另起新句。如：
- It’s raining hard; however, I think we should go out.
- It’s raining hard. However, I think we should go out.
雨下得很大，但我想我们还得出去。
_注意_：上例中的 however 不能换成 but，但可用 but 来改写 (注意所用标点的变化)。如：
- It’s raining hard, but I think we should go out.
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yet的用法
1. yet用作连词时，与but一样也主要用于转折，意为“但是”“而”
- I have failed, yet I shall try again. 我失败了，但我还要尝试。
- The judge was stern, yet completely fair. 法官很严峻，却完全公正。
- They are the same, yet not the same. 它们又一样，又不一样。
- It is strange, yet it is true. 那真是怪事，然而却是事实。
- I’ve been away only for three years, yet I can hardly recognize my hometown.
我仅在外三年，可我几乎认不出我自己的故乡了。 - He said he was our friend, yet he wouldn’t help us. 他说他是我们的朋友，但却不肯帮助我们。
2. 有时用在句首
- yet the house was cheerful. 但屋子里显得很欢快。
- yet its population has doubled. 但它的人口翻了一番。
3. yet有时可与并列连词and或but连用，构成习语and yet和but yet，意为“虽然如此”“可是”“然而”，与单独使用的yet意思相同
- He’s not really nice-looking, and yet he has enormous charm. 他并不十分好看，可是他很有魅力。
- She’s a funny girl, but yet you can’t help liking her. 她是一个奇怪的姑娘，但你禁不住会喜欢她。
- I gave him ten pounds (and) yet he was not satisfied. 我给了他十镑但他仍不满足。
- She’s vain and foolish, and yet people like her. 她很虚荣愚蠢，但人们却喜欢她。
- She drove very fast to the airport, but [yet, and yet, but yet] she missed the plane.她开快车去机场，可还是误了飞机。
4. 根据英语习惯，although不能与连词but搭配使用，但是although可以与yet搭配连用，此时的yet可视为副词
- Although we are poor, yet we are happy. 尽管我们穷，但我们很快活。
- Although we have made some progress, yet we still have a long way to go.
我们虽然取得了些进步，但还是远远不够的。
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while的用法
while 是大家比较熟悉的一个词，但是许多人对它的了解是不全面的，你可能只知道它表示“当……的时候”，甚至可能还知道它与when, as的用法区别。但是，非常遗憾，你所知道的这些东西都是有关 while 用法的“基础知识”，却不是一般英语考试的“考点知识”.
1. 表示时间的用法，其意为“当……的时候”
- We must strike while the iron is hot. 我们要趁热打铁。
- 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?
- Were there any calls for me while I was out? 我出去的时候，有人来过电话吗?
- She hates anyone listening while she is telephoning. 她打电话时不愿让任何人听。
2. 表示让步的用法，其意为“尽管”“虽然”
- 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。
- while the Internet is of great help, I don’t think it’s a good idea to spend too much time on it.
虽然因特网很有帮助，但我还是认为在其上花太多的时间不是个好主意。 - while we don’t agree we continue to be friends. 尽管我们意见不同，我们还是朋友。
- while I did well in class, I was a poor performer at games. 虽说我学习不错，我运动却不行。
- while a few became richer, many did not. 虽然一些人变得更富有了，但多数人并非如此。
3. 表示对比的用法，其意为“而”“但”
- In some places women are expected to earn money while men work at home and raise their children. 有些地方妇女挣钱，而男子则在家里持家和带孩子。
- I went swimming while the others played tennis. 我去游泳，而其余的人则去打网球了。
- Air is a fluid but not a liquid, while water is both a fluid and a liquid.
空气是流体不是液体，水是流体也是液体。 - 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。
Prices are rising sharply, while incomes are lagging far behind. 物价飞涨而收入却远远落后。
_注意_ ：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 some languages have 30 _or_ more different vowel sounds, others have five _or_ less.有些语言有30个或更多的元音，而其他语言只有5个或更少的元音。
- 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。
4. 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
- while (he 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。