一.连词的定义用来连接词,短语,或句子的词叫连词。连词是一种虚词,在句中不能单独使用。连词可分为两类:并列连词和从属连词。二.具体用法:1.并列连词并列连词用来连接具有并列关系的词,短语或句子。常见的并列连词有:(1)表并列关系的and,both…and,notonly…butalso,neither…nor,aswellas…(2)表选择关系的or,either…or…,whether…or…(3)表转折but,while,yet,however,whereas,nevertheless…(4)表因果关系的for,so,thus,hence…2.从属连词从属连词用来引导从句。常见的从属连词有:1)引导时间状语从句的after,before,when,while,as,until,till,since,assoonas等。2)引导地点状语从句的where,wherever3)引导原因状语从句的because,as,since,nowthat4)引导结果状语从句的sothat,so…that,such…that等。5)引导目的状语从句的sothat,inorderthat,incase,lest,forthepurposethat…6)引导方式状语从句的as,asif/though,theway…7)引导比较状语从句的than,as…as,notas/so…as8)引导条件状语从句的if,unless,aslongassolongas,onconditionthat,﹝﹞9)引导让步状语从句的though,although,evenif,eventhough,as,while,nomatter+特殊疑问词=特+ever。10)引导名词从句的that,whether,if…三.常用连词的用法辨析(1)while,when,aswhen/while的区别:when从句中的动词既可以是短暂动词,也可以是延续动词。而while从句中的动词只能是延续性动词。Whilemywifewasreadingthenewspaper,IwaswatchingTVWhenJohnarrivedIwascookinglunch.as表示“当......时”“随着”或“一边……一边…”,主句和从句的动作同时发生。TheyalwayssingastheywalkAsshelefttheroomsherememberedthatbook(2)as,because,since,for这四个词都可表原因,但用法有区别。1)because的语气最强。用why提问时用because回答。例如:Istayedathomebecauseitrained.---Whyaren’tyougoing?---BecauseIdon’twantto.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。Ashewasn’tready,weleftwithouthim.SinceIhavenomoney,Ican’tbuyanyfood.3)for用来补充说明一种理由。For引导的句子不放在句子的开头。Idecidedtostopandhavelunch----forIwasfeelingquitehungry.(3)if,whetherif和whether都可作“是否”讲,在引导宾与从句是一般可互换。Iwonderwhether(if)youstillstudyinthatschool.Idon’tknowwhether(if)helikesthatfilm.在下列情况下,只能用whether,不能用if:1)放在句首时。Whetherhewillcometothepartyisunknown.2)和ornot搭配时。Whetherthisistrueornot,Ican’tsay3)在不定式前,形容词后。Ihaven’tmadeupmymindwhethertogothereornot.(4)so…that,such...that1)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。I’msotiredthatIcan’twalkanyfarther.Itwassuchawarmdaythathewentswimming.2)如果在名词之前有many,much,little,few时,用so,不用such。Hehassolittleeducationthatheisunabletogetajob.IhavehadsomanyfallsthatIamblackandblueallover.(5)either…or…,neither…nor,notonly…butalso…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。Eitheryouorheiswrong.Neitherhenorhischildrenlikefish.Notonlytheteacherbutalsothestudentswanttobuythebook.(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“Althoughheisoversixty,butheworksashardasothers.”这个句子应改为:Althoughheisoversixty,heworksashardasothers.或Heisoversixty,butheworksashardasothers.(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“BecauseJohnwasill,soItookhimtothedoctor.”这个句子应改为BecauseJohnwasill,Itookhimtothedoctor.或Johnwasill,soItookhimtothedoctor.