状语从句状语从句主要用来修饰主句或主句的谓语。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。1．时间状语从句常用引导词：when,as,while,assoonas,while,before,after,since,till,until特殊引导词：theminute,themoment,thesecond,everytime,theday，theinstant,immediately,directly,nosooner…than,hardly…when,scarcely…when1).WhileJohnwaswatchingTV,hiswifewascooking.2).Thechildrenranawayfromthegardenthemomenttheysawtheguard.3).NosoonerhadIarrivedhomethanitbegantorain.（倒装语序）4).EverytimeIlistentoyouradvice,Igetintotrouble.比较until和till此两个连词意义相同。肯定形式表示的意思是"做某事直至某时"，动词必须是延续性的。否定形式表达的意思是"直至某时才做某事"。动词为延续性或非延续性都可以。正确使用这两个连词的关键之一就在于判断句中的动词该用肯定式还是否定式。肯定句：Isleptuntilmidnight.我一直睡到半夜时醒了。WaittillIcallyou.等着我叫你。（肯定句中可用before代替Let'sgetinthewheatbeforethesunsets.）否定句：Shedidn'tarriveuntil6o'clock.她直到6点才到。Don'tgetoffthebusuntilithasstopped.公共汽车停稳后再下车。Ididn'tmanagetodoituntilyouhadexplainedhow.直到你教我后，我才会做。1)Until可用于句首，而till通常不用于句首。Untilyoutoldme,Ihadheardnothingofwhathappened.直到你告诉我以前，出了什么事我一点也不知道。2)Untilwhen疑问句中，until要放在句首。---Untilwhenareyoustaying?你呆到什么时候？---UntilnextMonday.呆到下周一。表示"一…就…"的结构hardly/scarcely…when/before,nosooner…than和assoonas都可以表示"一…就…"的意思，例：Ihadhardly/scarcelygothomewhenitbegantorain.Ihadnosoonergothomethanitbegantorain.2．地点状语从句常用引导词：where特殊引导词：wherever,anywhere,everywhereGenerally,airwillbeheavilypollutedwheretherearefactories.Whereveryougo,youshouldworkhard.WhereIlivethereareplentyoftrees.我住的地方树很多。WhereverIamIwillbethinkingofyou.不管我在哪里我都会想到你。3原因状语从句常用引导词：because,since,as,since,for特殊引导词：seeingthat,nowthat,inthat,consideringthat,giventhat…1)..Nowthateverybodyhascome,let’sbeginourconference.2).Thehigherincometaxisharmfulinthatitmaydiscouragepeoplefromtryingtoearnmore.3).Consideringthatheisnomorethan12yearsold,hisheightof1.80misquiteremarkable.比较：because,since,as和for1）because语势最强，用来说明人所不知的原因，回答why提出的问题。当原因是显而易见的或已为人们所知，就用as或since。Ididn'tgo,becauseIwasafraid.Since/Astheweatherissobad,wehavetodelayourjourney.2）由because引导的从句如果放在句末，且前面有逗号，则可以用for来代替。但如果不是说明直接原因，而是多种情况加以推断，就只能用for。Heisa