副词性从句.doc

副词性从句（状语从句） 状语从句在复合句中做状语可修饰主句中的动词、形容词、和副词等。状语从句有从属连词引导，与主句相接。状语从句的位置可放在句首或句末。放在句首时，其后常用逗号，放在句末时，其前一般不用逗号。状语从句根据它们的含义一般可分为十大类，分别表示时间、地点、原因、目的、结果、条件、让步、比较、方式和程度状语从句。 一、 时间状语从句 常用的连词有：before, after, when, as(当，一边…一边), while(在…期间), whenever(无论何时，每当)，since(自从…以来)，as soon as/hardly …when/no sooner than (一…就…)，till /until。如果主句是一般将来时，状语从句中用一般现在时。since所引导的从句一般要用非延续性动词，主句用完成时态。 1. while, when, whenever和 as的用法比较 (1) while 常表示一段较长的时间或一个过程，强调主句的动词和从句的动词所表示的动作或状态是同时发生的。她不能表示一时性或暂时性的动作。 Don’t talk so loud while others are working.(别人工作时请勿大声说话.) While he was eating, I asked him to lend me 2 dollars.(当他正在吃饭时,我请他借给我二美元.) (2) when 引导的时间状语从句可以指时间的一点,也可以指一段时间,从句的谓语动词可用终止性动词,也可用延续性动词.when引导的从句表示具体的时间,从句的动作和主句的动作可以同时也可以先于主句的动作.whenever指任何一个不具体的时间. It was raining when we arrived.(我们到达时天正下着雨. 动作同时,指时间点) When you read the poem a second time, the meaning will become clearer to you. (当你再读一遍这首诗,你就更清晰它的含义. 动作有先后,指时间点,不能用while) (3) as 用as时主句和从句的动作往往同时发生,具有延伸意义,一般同延续性动词连用,有时可译作“一边…一边” As time went on, his theory proved to be correct.(随着时间的推移,他的理论被证明是正确的) As we walked, we talked.(我们边走边谈) 2. since 和 before 的用法比较 两者均可用于“ It be… since/before+从句”的句型.区别在于since 表示“自从…以来”,所在主从句的谓语动词的时态关系是：It is /has been sometime since sb. did sth.而before的含义是“(过了多久)才…”主从句的谓语动词的时态关系是: It was /had been sometime before sb. did sth.表过去和将来时,两者相应的句型分别是: It was some time since sb had done sth. 和It will be some time before sb does sth. It is 30 years since he joined the revolution.(他参加革命已三十年了.) It was three days before he came back.(他三天后才回来.) 二 地点状语从句 常用的从属连词有:where, wherever(无论哪里), everywhere(在每一个地方). After the war, a new school building was put up where there has once been a theatre. (战后一所新的学校在以前的剧院处建成.) She found her calculator where she lost it .(她在丢的地方找到了计算器) Everywhere they went ,the distinguished guests were warmly welcome