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。
(一)、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。
(二)、表选择的并列连词
主要 or (或者，还是，否则), either…or…(不是…就是…), neither…or…(既不…也不…), otherwise
(要不然)等。如：
Be careful about what you say or you may regret it. 当心你讲的话，否则你会后悔的。
Either say you’re sorry or else get out! 你要么道歉，要么滚开!
Neither does he smoke nor does he drink. 他既不抽烟也不喝酒。
Seize the chance, otherwise you will regret it. 要抓住机会，否则你会后悔的。
注：neither…nor…连接两个句子，注意用倒装语序。
(三)、表示因果关系的并列连词。
主要有 for(因为), so(因此)等。如：
He shook his head, for he thought differently. 他摇了摇头，因为他有不同想法。
He told me to do it, so I did it. 他让我这样做，于是我就这样做了。
The child had a bad cough, so his mother took him to the doctor.
这孩子咳得很利害，所以他妈妈带他去看医生。
You are supposed to get rid of carelessness, for it often leads to serious errors.
你们一定要克服粗枝大叶，因为粗枝大叶常常引起严重的错误。
注意：for表示结果通常不能放句首，也不能单独使用。
(四)、表示并列关系的并列连词。
这类连词主要有 and , or , either…or , neither…nor ,
not only…but (also) , both…and , as well as ，when(=and just at this time 就在这时)等。如：
Give him an inch and he will take a mile. 他会得寸进尺。
Not only did he speak more correctly, but he spoke more easily.
不仅他讲得更正确，也讲得更不费劲了。
He was about to go to bed when the telephone rang. 他正要上床睡觉，这时电话铃响了起来。
He didn’t go and she didn’t go either. 他没去，她也没去。
The weather is mild today; it is neither hot nor cold. 今天天气很温暖，不冷也不热。
Both New York and London have traffic problems. 纽约和伦敦都存在交通问题。
It is important for you as well as for me. 这对你和对我都很重要。
People who are either under age or over age may not join the army.
年龄不到或者超龄的人都不得参军。
(一)、引导时间状语从句的从属连词
1、表示“当…时候”或“每当”的时间连词。主要的 when, while, as, whenever。如：
Don’t talk while you’re eating. 吃饭时不要说话。
Vegetables are best when they are fresh. 蔬菜新鲜时最好吃。
He came just as I was leaving. 我正要走时他来了。
2、 表示“在…之前(或之后)”的时间连词。主要的有before, after。如：
Try to finish your work before you leave. 离开前设法把工作做完。
After we have finished tea, we will sit on the grass. 喝完茶之后我们将坐在草地上。
3、表示“自从”或“直到”的时间连词。主要的有since, until, till。如：
She’s been playing tennis since she was eight. 她从八岁起就打网球了。
Hold on until I fetch help. 坚持一下，等我找人来帮忙。
Never trouble trouble till trouble troubles you. (谚)不要无事惹事。
(二)、引导条件状语从句的从属连词。
这类连词主要有if, unless, as [so] long as, in case 等。如：
Do you mind if I open the window?我开窗你不介意吧?
Don’t come unless I telephone. 除非我打电话，否则你别来。
As long as you’re happy，it doesn’t matter what you do. 只要你高兴，你做什么都没关系。
In case it rains they will stay at home. 万一下雨，他们就呆在家里。
注意：在条件状语从句中，通常要用一般现在时表示将来意义，而不能直接使用将来时态。不过，有时表示条件的 if之后可能用 will，但那不是将来时态, 而是表示意愿或委婉的请求(will为情态动词)。如：
If you will sit down for a few moments, I’ll tell the manager you’re here. 请稍坐, 我这就通知经理说您来了。
(三)、引导目的状语从句的从属连词。
主要的有 in order that, so that, in case, for fear等。如：
He raised his voice so that everyone could hear. 他提高了嗓音，以便每个人都能听见。
Take your umbrella (just) in case it rains. 带上雨伞，以防下雨。
She repeated the instructions slowly in order that he should understand. 她把那些指示慢慢重复了一遍好让他听明白。
(四)、引导结果状语从句的从属连词。
主要的有so that, so…that, such…that等。如：
I went to the lecture early so that I got a good seat. 我去听演讲去得很早, 所以找个好座位。
I had so many falls that I was black and blue all over. 我摔了许多跤，以致于全身都是青一块紫一块的。
He shut the window with such force that the glass broke. 他关窗子用力很大, 结果玻璃震破了。
(五)、引导原因状语从句的从属连词
主要的有because, as, since, seeing (that), now (that), considering (that) 等。如：
He distrusted me because I was new. 他不信任我，因为我是新来的。
As you are sorry，I’ll forgive you. 既然你悔悟了，我就原谅你。
Since we’ve no money, we can’t buy it. 由于我们没钱，我们无法购买它。
Seeing that he’s ill he’s unlikely to come. 因为他病了，他大概不会来了。
Now that she has apologized, I am content. 既然她已经道了歉, 我也就满意了。
(六)、引导让步状语从句的从属连词。
主要的有although, though, even though, even if, while, however, whatever, whoever, whenever, wherever等。如：
Although they are twins, they look entirely different. 他们虽是孪生, 但是相貌却完全不同。
I like her even though she can be annoying. 尽管她有时很恼人, 但我还是喜欢她。
You won’t move that stone, however strong you are. 不管你力气多大, 也休想搬动那块石头。
Whatever we have achieved, we owe to your support. 我们取得的一切成就都归功于你们的支持。
Whoever you are, you can’t pass this way. 不管你是谁，你都不能从这里通过。
Whenever I see him I speak to him. 每当我见到他，我都和他讲话。
(七)、引导方式状语从句的从属连词。主要的有as, as if, as though, the way等。
如：
Why didn’t you catch the last bus as I told you to? 你怎么不听我的话赶乘末班公共汽车呢?
He bent the iron bar as if it had been made of rubber. 他将铁棍折弯，仿佛那是用橡皮做成的。
Nobody else loves you the way(=as) I do. 没有人像我这样爱你。
(八)、引导地点状语从句的从属连词。主要的有where, wherever, everywhere, anywhere等。
如：
The church was built where there had once been a Roman temple. 这座教堂盖在一座罗马寺庙的旧址。
I’ll take you anywhere you like. 你想到哪儿我就带你到哪儿。(from www.yygrammar.com)
Everywhere I go，I find the same thing. 不管我走到哪里，我都发现同样情况。
(九)、引导比较状语从句的从属连词。主要的有than和as…as。
如：
She was now happier than she had ever been. 现在她比过去任何时候都快活。
I glanced at my watch. It was earlier than I thought. 我看了看表，时间比我想像的早。
He doesn’t work as hard as she does. 他工作不像她那样努力。
(十)、引导名词从句的从属连词。
主要有that, whether, if 等，它们用于引导主语从句、表语从句、宾语从句和
同位语从句。其中that 不仅没不充当句子成分，而且没有词义，在句子中只起连接作用；而 if, whether
虽不充当句子成分，但有词义，即表示“是否”。如：
He replied that he was going by train. 他回答说他将坐火车去。
I wonder if it’s large enough. 我不知道它是否够大。
I worry about whether I hurt her feelings. 我为是否伤了她的感情而担心。
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)
两者均可表示转折或对比，意为“但是”、“可是”、“然而”等，但有区别：
1. 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。
2. 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。
3. 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.
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。如：
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。如：
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）。如：
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。
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”。请看下面两道考题：
1、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. 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、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。
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、考查表示对比的用法，其意为“而”“但”。如：
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、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 (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。
1、表示选择，意为“或”“还是”：
Is the radio off or on? 无线电关上了还是开着的?
Would you prefer tea or coffee? 你喜欢茶还是咖啡？
Is he asleep or awake? 他睡着了还是醒着?
Are you going to America by boat or by air? 你到美国是坐船还是坐飞机？
You may go or stay, according as you decide. 是去是留由你自己决定。
Are you from North China or South China? 你是华北人还是华南人?
2、表示一种否定的条件，意为“否则”：
Come on, or we’ll be late. 快点，否则我们要迟到了。
Hurry up, or you'll be late for school. 赶快，否则你上学就要迟到了。
Dress warmly, or else you’ll catch cold. 穿暖和点，否则你会感冒的。
Be careful, or you’ll break that vase! 小心，否则你会把那花瓶打碎!
Cross the road very carefully. Look both ways, or you might be knocked down. 过马路要非常小心，要看两边，不然会被车撞倒。
3、可表示“要不就是”：
He must be joking, or else he’s mad. 他一定在说笑话，要不就是疯了。
The book must be here, or else you’ve lost it. 这书一定在这儿，要不就是你丢失了。
4、用于否定句中代替and。
He was not clever or good-looking. 他不聪明，也长得不好看。
比较：
They sang and danced. 他们既唱歌又跳舞。
They didn't sing or dance. 他们既没有唱歌也没有跳舞。
5、用于习语
The work is more or less finished. 工作大体上完成了。
They consist of 1700 or more tribes. 他们由1700个或更多部族构成。
There’s just one or two details I want to make sure about. 还有一两个细节我想弄清楚。
Either your mother or your father may come with you. 你母亲或是你父亲会陪你去。
1、for用作连词，主要表示理由，用于引起的分句对前面的话进行解释，常用逗号把它和前面的分句分
开。如：
She was angry, for she didn’t know French. 她生气了，因为她不懂法语。
He must be out, for there is no light in the room. 他准是出去了，因为屋里没有灯。
He shook his head, for he thought differently. 他摇了摇头，因为他有不同想法。
The days were short, for it was now December. 白天很短，因为这时已经是十二月。
We rarely stay in hotels, for we can’t afford it. 我们很少住旅馆，因为我们住不起。
You needn’t have watered the flowers, for it is going to rain. 你本不必浇那些花，因为就要下雨了。
He took the food eagerly, for he has eaten nothing since dawn.
他狼吞虎咽地吃了起来，因为他从天亮就没吃过东西。
He was busy packing, for he was leaving that night.
他那时正忙着打点行李，因为那天晚上他就要走了。
She does not go out in the winter, for she feels the cold a great deal.
她冬天不出门，因为他特别怕冷。
2、for表示结果通常不能放句首，也不能单独使用。
1、for引导的从句不能位于它所解释的动词之前：
Because it was wet he took a taxi. 因为下雨，他叫了一辆出租车。（这里不能用for）
2、for引导的从句不能位于not, but或任何连词之后：
He stole, not because he wanted the money but because he liked stealing. 他偷东西，并不是因为他想要钱，而是他有这种毛病。（这里不能用for）
3、for引导的从句不能用于回答问题：
—Why did you do it? 你为什么这么做?
—I did it because l was angry. 因为我生气才这么做的。（这里不能用for）
4、for引导的从句不能单单用来复述已讲过的话，而必须包括新的内容：
He spoke in French. She was angry because he had spoken in French. 他讲法语。因为他讲法语，她生气了。（这里不能用for）
但是说：
She was angry, for she didn’t know French. 她生气了，因为她不懂法语。（这里用for是正确的，也可用because）
注意：之所以有这些用法上的限定，其理由是for引导的从句不能直接说明某一特定动作发生的原因，而只能提供一些起帮助解释作用的附加说明。例如：
The days were short, for it was now December. 天短了，现在已是12月了。
He took the food eagerly, for he has eaten nothing since dawn. 他狼吞虎咽地吃了起来，因为他从天亮就没吃过东西。
When I saw her in the river I was frightened. For at that point the currents were dangerous. 我看见她在河里时，吓坏了。那个地方水流非常危险。
注意：在口语中，for从句前常稍停一下。在笔语中，在此处常有一个逗号。有时也用一个句号断开，如最后一个例子所示。上面三个例句中也可用becatse, 但用for更好些。
1、so用作连词，主要用于表结果，意为“所以”：
It’s very cold, so wear a heavy coat. 外边很冷，因此穿一件厚大衣。
The door was locked, so we couldn’t get in. 门上锁了，所以我们进不去。
I couldn’t have won, so I didn’t go in for the race. 我不可能获胜，因此我没参赛。
The play began at eight, so they must dine at seven. 戏八点开始，因此他们必须七点吃饭。
It was dark, so I couldn’t see what was happening. 天很黑，所以我看不见发生了什么事。
There happened to be a policeman on the corner, so I asked him the way. 恰好拐角处有一位警察，我就向他问路了。
2、有时可与并列连词and连用，构成习语and so(相当so)：
He told me to do it and so I did it. 他叫我那么做，所以我就做了。
He worked hard and so he succeeded. 他勤奋工作，所以他取得了成功。
There was so much to eat and so few people to eat it. 有这么多东西可吃，而吃的人又这么少。
I forgot to post the letter, and so she never heard about my divorce. 我忘了寄那封信了，所以她一直不知道我离婚的事。
3、不要按汉语意思将“因为…所以…”直译为because…so…：
误：Because he was ill, so he couldn't come.(去掉because或so中任意一个)
1. 基本义为“和”“又”“而且”等，但它有时还可表示对比或转折，相当于汉语的“而”“但”“却”。如：
She’s a bank manager and I’m just a road-sweeper. 她是银行经理，而我不过是个扫街的。
I’ve read Tony’s book and I don’t understand it. 我读过托尼的书，但我不懂。
He hasn’t had anything published and he calls himself a writer! 他什么都没发表过，却自称作家！
2. 有时用于连接两个相同的词语，主要有以下用法：
(1) 连接两个相同的比较级，表示“越来越……”。如：
The weather is getting colder and colder. 天气越来越冷了。
Your English is getting better and better. 你的英语越来越好了。
Computers are becoming more and more complicated. 计算机变得越来越复杂。
(2) 连接两个相同的动词，表示动作的反复或连续。如：
He coughed and coughed. 他咳个不停。
He tried and tried but without success. 他试了又试却未成功。
(3) 连接两个相同的副词，也表示动作的反复或连续。如：
He kept moaning on and on. 他呻吟不已。
(4) 连接两个相同的名词，有以下两种主要用法：
①表示“许多”。如：
They talked for hours and hours. 他们谈了很长很长时间。
The road went on for miles and miles. 这条路很长很长。
②强调差别，意为“与……不同”。如：
Don’t worry there are rules and rules. 别担心——规则跟规则不一样。
I like city life but there are cities and cities. 我喜欢城市生活，但城市之间也有差别。
3. 在come和go以动词原形出现时，其后习惯上不跟不定式表示目的，而是用“and+动词原形”表示目的。如：
I must go and help my mother. 我必须去帮助我母亲。
I’ll come and check the accounts. 我将来清理账目。
Go and buy yourself a new pair of shoes. 去给自己买双新鞋吧。
Come and play a game of bridge with us. 来跟我们一起打桥牌吧。
注意：但是，如果go和come不是以动词原形出现，而是以过去式、过去分词、现在分词、动名词等方式出现，则其后应不定式表示目的。如：
I’ve come to collect my book. 我来取我的书。
I’ m thinking of going to look for mushrooms. 我想去采蘑菇。
I didn’t come to talk to Bill; I came to talk to you. 我不是来跟比尔说话的，我是来跟你说话的。
I went to buy a newspaper and lost my place in the queue. 我去买了份报纸，回来就找不到我排队中的位置了。
另外，在come, go 之后的 and 有时可以省略（尤其在美国英语中）。如：
I’ll come (and) see you later. 我晚些时候再来看你。
4. 用在祈使句后，表示结果，意为“那么”（暗示一种条件）。如：
Work hard and you’ll pass the examinations (=If you work hard, you’ll pass the examinations). 努力吧，你考试会及格的。
Arrive late once more and you’re fired (=If you arrive late once more, you’re fired). 再迟到一次，就把你开除。
有时也可以不是用于祈使句后表示结果。如：
One more step and I will fire. 你再动一步，我就要开枪了。
5. 用在 good, nice, fine 等之后，表示“很”“挺”。如：
I won’t go until I’m good and ready. 我完全准备好了才去。
Make sure you cut the bread nice and thick. 你一定要把面包片切得厚厚的。
6. 在主从复合句中，不要在主句前误加 and。如：
使用两个镜子能看见自己的头的后部。
误：If you use mirrors, and you can see the back of your head.
正：If you use mirrors, you can see the back of your head.
7. 某些用 and 连接的两个词，与汉语顺序相反，不要按汉语词序颠倒过来。如：
rich and poor 贫富 land and water 水陆
right and left 左右 north and south 南北
food and drink 饮食 food and clothing 衣食
8. 比较以下各组句子有无连词 and 的差别：
天气晴朗，我们出去散了步。
正：The weather being fine, we went out for a walk.
正：The weather was fine, and we went out for a walk.
教室里包括老师有5个人。
正：In the classroom there are five people, the teacher included.
正：In the classroom there are five people, and the teacher was included.
他有两个小孩，都很顽皮。
正：He has two children, both of whom are naughty.
正：He has two children, and both of them are naughty.
as 用作连词用法如下：
1、表示伴随，意为“随着”。如：
As time passed, things seemed to get worse. 随着时间的推移，情况似乎变得更糟了。若其后不接从句，而接名词，则用介词 with 表示“随着”。如：
With the development of modern agriculture and industry, more and more waste is produced.
随着现代工农业的发展，污染越来越严重了。
2、表示让步，意为“虽然”“尽管”，要用于倒装句（相当于 though，但语气稍弱）。如：
Boy as he was, he behaved like a girl. 他虽然是个男孩，但举止却像个女孩。
Much as I like you, I couldn’t live with you. 我尽管很喜欢你，却不能和你一起生活。
Try as he would [might]，he couldn’t open the door. 他试过多次了，却仍打不开门。
3、表示时间，意为“当……时候”。如：
He dropped the glass as he stood up. 他站起来时，把杯子摔了。
As I was coming here, I met your brother. 我来这里时碰到了你的弟弟。
注意，as 引导时态状语从句时，其谓语动词通常只能是动作动词，而不能是静态或状态动词。如：
她出生后不久父母双亡，是由姑母抚养大的。
误：Her parents died as she was a baby and she was brought up by her aunt.
正：Her parents died when she was a baby and she was brought up by her aunt.
4、表示原因，引导原因状语从句时，其谓语动词可以是动作动词，也可以是状态动词。如：
As you weren’t there I left a message. 因为你不在那里，我留了个信儿。
另外，引导原因状语从句，可用以下这样的倒装语序。如：
Tired as she was, I decided not to disturb her. 因为她累了，我就决定不打扰她了。
Writing hurriedly as she was, she didn’t notice the spelling errors. 因为写得仓促，她没有注意其中的拼写错误。
两者在表示“是否”时的用法区别如下：
1. 互换的场合
引导宾语从句表示“是否”时, 两者常可互换。如：
He asked if [whether] we wanted a drink. 他问我们是否想喝一杯。
He didn’t tell me if [whether] he would come. 他没有告诉我他是否会来。
注：若是引导条件状语从句，则只能用 if (意为“如果”)。
2. 通常用 if 的场合
当引导一个否定的宾语从句时，通常用 if 而不用 whether。如：
I don’t care if it doesn’t rain. 我不在乎天是否下雨。
注：在个别词语 (如 wonder, not sure 等)后的从句否定式有时也可能用 whether 来引导。如：
I wonder if [whether] he isn’t mistaken. 我想知道他是否错了。
3. 通常用 whether 的场合
(1) 引导主语从句且放在句首时。如：
Whether he will come is still a question. 他是否会来还是个问题。
注：若在句首使用形式主语 it，而将主语从句放在句末，则有时也可用 if 来引导。如：
It was not known whether [if] he would come. 不知他是否会来。
(2) 引导表语从句时。如：
The question is whether we should go on with the work. 问题是我们是否应该继续进行这项工作。
注：引导表语从句偶尔也用 if (很不正式)，但远不如用 whether 常见。
(3) 引导宾语从句且放在句首时。如：
Whether he is single I don’t know. 他是否单身，我不知道。
(4) 引导让步状语从句时。如：
Whether he agrees or not, I shall do that. 不管他同意与否，我都要那样做。
(5) 与 or 连用分别引导两个从句时。如：
I don’t know whether he is wrong or she is wrong. 我不知道是他错了，还是她错了。
注：or 若不是引导两个从句，而是连接两个词或短语，则也可用 if (但不如用 whether 常见)。如：
He didn’t know if [whether] we should write or phone. 他不知道我们是写信好还是打电话好。
(6) 用于不定式之前时。如：
I’m not sure whether to stay or leave. 我不知是留还是去。
I didn’t know whether to laugh or to cry. 我真是哭笑不得。
(7) 用于介词之后时。如：
It depends on whether the letter arrives in time. 这取决于信是否来得及时。
I worry about whether I hurt her feelings. 我担心是否伤了她的感情。
(8) 直接与 or not 连用时。如：
I will write to you whether or not I can come. 我能不能来，我将写信告诉你。
注：若不是直接与 or not 用在一起，则有时也可用 if。如：
I don’t know whether [if] he will win or not. 我不知他是否能赢。
(9) 在某些动词后(如 discuss 等) 通常只用 whether。如：
We discussed whether we should hold a meeting. 我们讨论了是否要开一个会。
unless和if not均可表示“如果不”，有时用法相同，有时不同，请看题：
You’ll miss the train __________ you hurry up.
A. unlessB. as C. if notD. until
此题应选 A。容易选C。其实C只是词序不对，若改为...if you don’t hurry up 也是对的。在许多情况下，连词until与if...not同义，且可换用(表示一种否定的条件)。
要是不下雨，我们就去。
正：We shall go unless it rains.
正：We shall go if it doesn’t rain.
我不打电话给你，你就不要来。
正：Don’t come unless I phone you.
正：Don’t come if I don’t phone you.
从以上两例可以看出，unless有时可以与if not换用，但if not中的not必须位于从句谓语中，而不能直接与if连用在一起。但是注意，即使如此，两者也并不是永远可以换用的：
一般说来，两者互换的场合只限于：当我们要去结束一个已经存在的想法或状态时（而不是去开始一种新的想法或状态)。试体会：
I’ll stay at home unless I am invited (=if I am not invited) to the party. 要是不邀请我去参加晚会，我就呆在家里。 (即“邀请我参加晚会”会结 束“我将呆在家里”这一现在的打算)
若要表示所述条件会导致一种新的想法或情况，通常要用if...not，而不用unless。试体会：
I’ll be angry if I’m not invited to the party. 如果不邀请我参加晚会，我会生气的。(即“不邀请我去参加晚会”会导致一种新情况—-“我会生气”)
in case用作连词时有以下两个用法：
1. 表示条件，意为“如果”“万一”。如：
In case it rains, do not expect me. 如果下雨，就不要等我了。
In case you see him, ask him about it. 如果你见着他，问问他这事。
In case I forget, please remind me of my promise. 如果我忘了，请提醒我我的诺言。
In case he arrives before I get back, please ask him to wait. 如果他在我回来之前到，请让他等等我。
2. 表示目的，意为“以防”“生怕”。如：
I’m shy of buying shares in case I lose money. 我不敢买股票，怕赔钱。
Take warm clothes in case the weather is cold. 带些暖和的衣服，以防天气变冷。
I’ll keep a seat for you in case you should change your mind. 我给你留一个座位，以防你会改变主意。
We took our swimming things in case we happened to find a pool. 我们带上游泳用品，以备万一能找到一个水池。
注：有时中间的谓语由 should构成，强调偶然性，可译为“万一”：
I wrote down her address in case I should forget it. 我写下了她的地址，以防万一我忘了。
I always slept by the phone in case he should ring during the night. 我总是睡在电话机旁边，怕万一他夜间打电话来。
1. 表示原因，语气较强，可用来回答 why 提出的问题。如：
A：Why do you love her? 你为什么爱她?
B：Because she is kind. 因为很善良。
2. because 除经常用于引导原因状语从句外，还可引出表语从句或用于强调句等。如：
It is because you’re eating too much. 那是因为你吃得太多了。
It was because I wanted to buy a dictionary that I went to town yesterday. 我昨天是由于想买本字典而进城的。
3. 汉语说“因为……所以……”，但英语却不能用 because…so…这样的结构。如：
因为我病了半年，所以把工作丢了。
误：Because I was ill for six months, so I lost my job.
正：Because I was ill for six months, I lost my job.
正：I was ill for six months, so I lost my job.
4. 汉语说“之所以……是因为……”，英语可以类似以下这样的句型（用that比用 because普通）。如：
The reason (why) I’m late is that [because] I missed the bus. 我迟到的原因是因为我没有赶上公共汽车。
传统语法认为这类句型不能用 because, 但在现代英语中用because 的情形已很普遍。
5. 在not…because…这一结构中，not 有时否定主句，有时否定从句，具体视语境而定。一般说来，若 not 否定主句，最好在because 之前用逗号，否则会引起歧义，如下句在没有特定上下文时就有两种解释：
I didn’t go because I was afraid.
这个句子既可理解为“我没有去是因为怕”，也可理解为“我不是因为怕才去”。但是，如果because之前有副词just修饰，一般认为not是否定从句而不是主句。如：
You shouldn’t get angry just because some people speak ill of you. 你不要因为有人说你坏话而生气。
6. 有时可引导一个句子作主语，此时通常采用just because这样的形式，并且主句谓语动词通常（当然不是一定）为mean。如：
Just because you speak English doesn’t mean you can teach it. 你会说英语并不意味着你能教英语。
Just because you’re old doesn’t mean you have to be idle.
只是因为你年纪大了，这并不意味着你就应该懒散不活动。
Because you have words with your wife is no reason to smash up things. 你和你的妻子吵架并不能成为摔东西的理由。
7. 用于构成复合介词because of，其后可接名词、代词、 动名词、what 从句（但不能是that从句或没有引导词的从句）等。如：
He is here because of you (that). 他为你（那事）而来这里。
We said nothing about it, because of his wife’s being there. 因为他妻子在那儿，我们对此只字未提。
He left the company because of what the boss said at the meeting. 他离开了这家公司，是因为老板在会上讲的话。
8. because of通常用来引导状语，而用于不引导表语（引导表语时可用 due to）。如：
误：His absence is because of the rain.
正：His absence is due to the rain. 他因雨未来。
但是，若主语是代词（不是名词），则它引出的短语也可用作表语。如：
It is because of hard work. 那是因为辛苦工作的原因。
It will be because of money. 那将都是因为钱的原因。
四者均可用来表示原因，区别如下：
(1) 关于 because：语气最强，表示直接原因，可用于回答 why 提出的问题、引导表语从句、用于强调
句等，而其余三者均不行：
“Why didn’t he come?” “Because he was ill.” “他为什么没来?”“因为他病了。”
My stomach hurts because I have eaten too many apples. 我肚子痛，因为苹果吃得太多。
It is because he is honest that I like him. 是因为他诚实我才喜欢他。
(2) 关于 since 与 as：
a. 两者所表示的原因都是人们已知的，即对已知事实提供理由，而不是表示直接原因。since 比 as 语气稍强，且比 as 略为正式，它们引导的从句通常放在主句之前，有时也放在主句之后：
As you weren’t there, I left a message. 由于你不在那儿，我留了个口信。
Since you are wrong, you should apologize. 你既然错了，就应该道歉。
b. since 可用于省略句，而其他三者不行：
Since so, I have nothing to say. 既然如此，我无话可说。
(3) 关于 for：是并列连词(其余三者为从属连词)，它有时可表示因果关系(通常要放在主句之后，且可与because 换用)；有时不表示因果关系，而是对前面分句内容的解释或推断(也要放在主句之后，但不能与because 换用)。比较：
The ground is wet, for (=because) it rained last night. 地面是湿的，因为昨晚下过雨。
It must have rained last night, for the ground is wet this morning. 昨晚一定下过雨，你看今天早上地面是湿的。 (此句不能用 because 代 for)
1、如果是作为自由搭配in that，那么它的意思需视上下文而定。如：
Put the bookcase in that corner. 把书柜放在那个角落里。
You ought on no account to take part in that. 你千万别参与那事。
It is expensive to stay in that hotel. 住那家旅馆很贵。
2、如果用in that引导从句，则它是一个习语，意思是“因为”“由于”，与从属连词because意思相同。如：
She was fortunate in that she had friends to help her. 她很幸运，有一些朋友帮助她。
The situation is rather complicated in that we have two managing directors. 由于我们有两位总经理，所以情况很复杂。
I’m in a slightly awkward position, in that he’s not arriving until the 10th. 我的处境有点难堪，因为他要10号才来。
1. 用作连词，表示“虽然”，两者大致同义，可换用，只是 although 比 though 更为正式。如：
Though [Although] they’re expensive, people buy them. 虽然它们很昂贵，人们还是买。
2. although 一般不用作副词，而 though 可用作副词，表示“可是”“不过”。如：
I expect you’re right—I’ll ask him, though. 我认为你说得对——我去问问他也好。
She promised to phone. I heard nothing, though. 她答应要打电话来. 可我没听到回信儿。
这样用的though通常位于句末，但有时位于句首的though也有这样的意思。如：
他说他要付钱，然而我认为他不会付的。
正：He says he’ll pay, though I don’t think he will.
正：He says he’ll pay; I don’t think he will, though.
3. 在 as though（好像，仿佛），even though（即使，纵然）等固定短语中，不能用 although代替though。如：She treats me as though I were a stranger. 她待我仿佛我是一个陌生人。
He’s the best teacher even though he has the least experience. 他尽管经验最少，但教得最好。
4. 两者均可用于省略句，通常见于主句与从句主语相同，且从句谓语含有动词be的情形。如：
Although [Though] (it was) built before the war, the engine is still in perfect order. 尽管是战前制造的，这台发动机仍然处于良好状态。
Although [Though] (he is) still young he is going very grey. 尽管他还年轻他的头发却已变得灰白。
Although [Though] (she was) in pain, she bravely blinked back her tears. 她虽然很疼痛，但还是硬把眼泪抑制住了。
5. 当though用于倒装形式，它不能换成although，但可换成as。
Successful though [as] he is, he is not proud. 他虽然成功，但不骄傲。
Much though [as] I like you, I couldn’t live with you. 我尽管很喜欢你, 却不能和你在一起生活。
Try though [as] I would, I could not make her change her mind. 不管我多努力，也不能让她改变主意。
Surrounded though [as] we were by the enemy, we managed to march forward. 虽然我们被敌人包围着，但我们还是设法前进了。
Raining hard though [as] it is, I’m going out for a walk. 虽然正在下着大雨，我还是要出去散步。
注意，若倒装后置于句首的是名词时，其前习惯上不用冠词或其他限定词。如：
Expert though [as] he was, he failed. 他虽是专家，但还是失败了。
Big puzzle though [as] it was, it hadn’t got the better of Jim. 虽然是个大难题，但仍没有难倒吉姆。
6. 不要按汉语“虽然……但是……”的表达习惯，在 although 后连用 but。如：
虽然他只是个业余爱好者，但却是一流的高手。
误：Although he’s only an amateur, but he’s a first-class player.
正：Although he’s only an amateur, he’s a first-class player.
但是在强调时，although 可与 yet, still 等副词连用。如：
Though he seems happy, yet he is worried. 虽然他看起来很幸福，但他实际上很烦恼。
注意：值得一提的是，在某些特定的语境中，although 与 but 连用的句子是可能的（注：but 引出的句子在 although 从句之前）。如：
But I didn’t know that then, although I learned it later. 但我当时的确不知道此事，尽管后来还是知道了。
He wanted to go abroad, but although he had some money he couldn’t afford it. 他想出国，尽管他有些钱，但还是负担不起。
I tried doing the accounts, but although I knew some maths I found it very difficult. 我试着算这些账，但尽管我懂点数学，仍感到很困难。
分析：此句将 but 与 although 用在一起，但此句也没有错误。该句从总体来看，它是一个以并列连词 but 连接的并列句，而在该并列句的后面一句又是一个包含让步状语从句 although I knew some maths 的复合句——这种句型就是所谓的并列复合句。此句也可改写为 I tried doing the accounts, but I found it very difficult although I knew some maths.
其意为“…和…都”、“不但…而且…”、“既…又…”：
She both speaks and writes Japanese. 她不仅会说日语，而且还会写。
He spoke with both kindness and understanding. 他说话既亲切又明事理。
【注】作为关联并列连词，它通常应连接两个相同性质的句子成分，但有时后一成分可能省略与前一成分相同的词。另外，若连接两个成分作主语时，谓语要用复数：
Both she and Sophia were pleased with the girl. 她和索菲娅都喜欢这姑娘。
1、either…or…主要用于表示选择，其意为“要么……要么……”，“不是…就是…”，“或者……或者……”，用于连接两个性质相同的词或短语。如：
Either come in or go out. 要么进来，要么出去。
I want to visit either Paris or London. 我想去巴黎或伦敦游览一下。
Either he did not speak distinctly or I did not hear well. 不是他没讲清楚，就是我没听明白。
You can have either this one or that one. 你拿这个或那个都可以。
You must either go at once or wait till tomorrow. 你要么马上走，要么等到明天。
We can finish the work either this week or next week. 不是这星期就是下星期我们就可完成这项工作。
注意1：either…or…通常应连接两个相同性质的句子成分，但有时后一成分可能省略与前一成分相同的
词，若连接两个成分作主语，谓语动词通常与其靠近的主语保持一致。如：
Either you or I am to go. 你或我必须有人去。
Either he or you are right. 要么他对，要么你对。
注意2：但在非正式文体中，有时也会一律用复数谓语。如：
You can either have tea or coffee. 你喝茶也行，喝咖啡也行。
Either you or I am wrong. 不是你错，就是我错。
If either David or Janet come, they will want a drink. 大卫或珍妮特来的话，是会要喝酒的。
2. either…or…除可连接两个词或短语外，有时也可连接两个句子。如：
Either you must improve your work or I shall dismiss you. 要么你改进工作，要么我就辞退你。
Either you’ll leave this house or I’ll call the police. 你要是不离开这座房子，我就叫警察来。
3. either…or…的否定式可以是not either…or…，也可以是neither…nor...。如：
He didn’t either write or phone.=He neither wrote nor phoned. 他既没写信又没打电话。
注意，正如不能说either…not 一样(但可说not…either)，英语习惯上也不说either…or…not，如不能说：
Either he or his wife hasn’t come. 可改为：Neither he nor his wife has come.
其意为“既不…也不…”、“…和…都不”：
I have neither time nor money. 我既无时间又无钱。
I neither smoke nor drink. 我既不抽烟也不喝酒。
He neither knows nor cares what happened. 他对所发生的事不闻不问。
This is neither my fault nor yours. 这既不怪我，也不怪你。
【注】通常应连接两个相同性质的句子成分，但有时后一成分可能省略与前一成分相同的词。若连接两个成分作主语，其谓语通常与靠近的主语保持一致：
Mary neither likes maths nor (likes) history. 玛丽既不喜欢数学也不喜欢历史。
Neither Jim and Jack was at home. 吉姆和杰克都不在家。但在非正式文体中也可一律用复数：
Neither Jim and Jack were at home. 吉姆和杰克都不在家。
not only…but also表示“不但…而且…”，“不仅……而且”，“既……又”，用于连接两个性质相同的词或短语。如：
Not only men but also women were chosen. 不仅仅是男的，女的也有被选中的。
We were not only hungry, but also tired. 我们不但饿了，而且也累了。
She likes not only music but also sport. 她不但喜欢音乐而且喜欢运动。
She not only plays well, but also writes music. 她不仅很会演奏，而且还会作曲。
We go there not only in winter, but also in summer. 我们不仅冬天去那儿，而且夏天也去。
另外，在使用not only…but also…时还应注意以下几点：
1、有时可将but also分开用，即将but视为普通的并列连词，用于连接两个句子，然后将also用于句中（用谓语动词用在一起）。如：
He’s not only very fast, but he’s also got marvellous technique. 他不仅很快，而且技术高超。
2. 该结构中的also有时可以省略，或将also换成too, as well（置于句末）。如：
Not only is he funny, but he is witty too [as well]. 他不但风趣，而且也很机智。
He not only washed the car, but polished it too [as well]. 他不仅冲洗汽车，而且还擦拭了它。
His name is known not only in Japan, but in China. 他不仅在日本出名，而且在中国也出名。
3. 有时因为语境的需要，not only…but also…也可能用于连接两个性质不同的词或短语，但这多半因为承前省略的原因。如：
He not only goes to work on weekdays, but also on weekends. 他不仅工作日去上班，在周末也去上班。
句中的not only后接的是谓语goes to，而but also后接的却是状语 on weekends，可视为but also后承前省略了谓语动词 goes to work。
4. 当not only…but also连接两个主语时，谓语动词的数原则上与其相近的主语保持一致。如：
Not only the students but also their teacher is enjoying the film. 不仅学生们在欣赏这部影片，他们的老师也在欣赏这部影片。
5. 为了强调，可将not only置于句首，此时其后的句子通常要用部分倒装的形式。如：
Not only has she been late three times, she has also done no work. 她不仅仅迟到了3次，她还没干一点活。
Not only do they need clothing, but they are also short of water. 他们不但需要衣服，而且还缺水。
注：有时也可见到不倒装的情形，此时主要见于but also后接省略结构的情况（省略只剩下主语）。如：
Not only my mother was unhappy, but Marian, too. 不仅我母亲不快乐，玛丽安也不快乐。
1、连接对称结构
not only…but also…是一对非常有用的关联连词，其意为“不仅……而且……”“不但……而且……”，通常用于连接两个相同的句子成分，即所谓的“对称结构”。如：
(1). 连接主语
Not only you but also I am hungry. 不只你，我也饿了呢。
Not only men but also women were chosen. 不仅仅是男的，女的也有被选中的。
Not only the students but also their teacher is enjoying the film. 不仅学生们在欣赏这部影片，他们的老师也在欣赏这部影片。
(2). 连接谓语
She not only plays well, but also writes music. 她不仅很会演奏，而且还会作曲。
He not only read the book, but also remembered what he read. 他不仅读过这本书，还记得内容。
She not only sings like an angel, but also dances divinely. 她不但唱歌唱得像天使一样，而且跳舞也跟天仙一般。
(3). 连接表语
He is not only arrogant but also selfish. 他不但傲慢，而且自私。
The place was not only cold, but also damp. 那个地方不但很冷而且很潮湿。
Certain poisons, used as medicines in small quantities, prove not only innocuous, but beneficial. 某些毒品，如少量用作药品，证明不但无毒，而且有益。
(4). 连接宾语
He speaks both French and English well. 他法语和英语都说得好。
She likes not only music but also sport. 她不但喜欢音乐而且喜欢运动。
If this project fails it will affect not only our department, but also the whole organization. 要是这个方案不成功，这不仅不会影响我们这个部门，而且会影响整个组织。
(5). 连接定语
There are problems not only with the students, but also with the teachers themselves. 不但学生们有难题，教师们自己也有。
(6). 连接状语
We go there not only in winter, but also in summer. 我们不仅冬天去那儿，而且夏天也去。
He works not only on weekdays but on Sundays as well. 他不仅平时工作，星期日也工作。
They landed up not only having to apologize but also offering to pay. 他们最后不但同意道歉，而且还要付款。
2、连接非对称结构
但在实际运用中，该结构有时不完全遵循“连接相同句子成分”的用法而出现一些非对称结构。这类用法主要有以下几类：
(1). 因承前省略而导致的不对称
(1) He not only goes to work on weekdays, but also on weekends. 他不仅工作日去上班，在周末也去上班。
句中的not only后接的是谓语goes to，而but also后接的却是状语 on weekends，可视为but also后承前省略了谓语动词 goes to work。
(2) She not only plays the piano, but also the violin. 他不仅弹钢琴，而且还拉小提琴。
句中的not only后为谓语动词，而but also后接的是名词，实为动词plays的宾语，可视为在but also后承前省略了谓语动词plays。
(3) Her charm not only consists in her beauty but also in her self-confidence. 她的魅力不仅在于她的美貌，而且在于她的自信。可视为but also后承前省略了consists。
(2). 因强调导致不对称
有时为了强调，not only…but also…连接的两个成分也可能是“不对称”的，这类用法尤其见于not only后接的是句子的一个部分，而but却用于句中“连接”一个句子（其后的句中可能出现also，也可能省略also）。如：
It’s not only useless to trouble him but it is needless to do so.去麻烦他不仅没有用而且没有必要。
He’s not only very fast, but he’s also got marvellous technique. 他不仅很快，而且技术高超。
His headache and fatigue not only subsided, but, what is more, his craving for alcohol disappeared. 不但他的头疼和疲劳减累轻了，而且他嗜酒的毛病也消失了。
这类用法有时也可能会省略but后面的主语，而保留其后的谓语。如：
The film was not only amusing, but gave a valuable moral lesson. 这部电影不但逗人，而且也上了一堂有价值的道德教育课。（句子后半部分可视为but it gave a valuable moral lesson之省略）
She was not only the largest ship that had ever been built, but was regarded as unsinkable. 这艘轮船不仅是造船史上建造的最大的一艘船，而且也被认为是不会沉没的。（句子后半部分可视为but she was regarded as unsinkable之省略）
These attracted many visitors, for they were not only of great architectural interest, but contained a large number of
beautifully preserved frescoes as well. 它们吸引大量游客，不仅是因为建筑风格奇特，而且还有大量保存完好的壁画。
综合自：
https://m.yixuela.com/article/104
https://m.yixuela.com/article/105
https://m.yixuela.com/article/106
https://m.yixuela.com/article/107