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。连词主要可分为4类：并列连词.转折连词.选择连词和因果连词。连词也可以分为2类：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。

　　今天，我们主要讲解的是并列连词的基本用法。

　　并列连词

　　常见并列连词

　　表示转折关系的并列连词：主要有 but(但是), yet(可是), while(而，却)等。

　　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。

　　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。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。

　　表示因果关系的并列连词：主要有 for(因为), so(因此)等。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。

　　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。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。

　　常见并列连词用法

　　and：和，并且

　　I like basketball， football and table-tennis.我喜欢篮球、足球和乒乓球。

　　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。

　　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。