摘要： 常用连词的用法辨析 (1) while, when, as 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. (2)as, because, since , for 这四个词都可表原因.但用法有区别. 1) 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.例如: I stayed at home because it rained. ---Why aren’t you going? ---Because I don’t want to. 2) 如果原因已被人们所知.或不如句子的其它部分重要.就用as或since.Since比as稍微正式一点.As和since 引导的从句一般放在句子的开头.例如: As he wasn’t ready, we left without him. Since I have no money, I can’t buy any food. 3) for用来补充说明一种理由.因此.for引导的从句几乎可以放在括号里.For引导的句子不放在句子的开头.例如: I decided to stop and have lunch----for I was feeling quite hungry. (3)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. 在下列情况下.只能用whether,不能用if: 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. (4)so-that, such...that 1) so-that中的so是个副词.其后只能跟形容词或副词.而such...that中的such是个形容词.后接名词或名词短语.例如: I’m so tired that I can’t walk any farther. It was such a warm day that he went swimming. 2) 如果在名词之前有many, much, little, few时.用so,不用such.例如: He has so little education that he is unable to get a job. I have had so many falls that I am black and blue all over. (5)either-or-, neither-nor, not only-but also- 这三个连词词组都可连接两个并列成分.当它们连接两个并列主语时. 谓语动词要随相邻的主语变化.例如: Either you or he is wrong. Neither he nor his children like fish. Not only the teacher but also the students want to buy the book. (6)although, but 这两个连词不能用在同一个句子中.例如:我们不能说“Although he is over sixty, but he works as hard as others. 这个句子应改为:Although he is over sixty, he works as hard as others.或He is over sixty, but he works as hard as others. (7)because, so 这两个连词同样不能用在同一个句子中.例如:我们不能说“Because John was ill, so I took him to the doctor. 这个句子应改为Because John was ill, I took him to the doctor.或John was ill, so I took him to the doctor. [实例解析]

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