状语从句是用来修饰主句中的动词,副词和形容词的从句。根据其含义状语从句可分为时间状语从句,地点状语从句,条件状语从句,原因状语从句,结果状语从句,比较状语从句,目的状语从句,让步状语从句。 1.时间状语从句 (1)时间状语从句常用when,as,while,before,after,since,till,until,assoonas等连词来引导。例如: Itwasraininghardwhengottoschoolyesterday. Whilehewasdoinghishomework,thetelephonerang. Ashewalkedalongthelake,hesanghappily. HehadlearnedalittleChinesebeforehecametoChina. Afterhefinishedmiddleschool,hewenttoworkinafactory. (2)在时间状语从句里,通常不用将来时态,用现在时态表示将来的动作或状态。例如: I’llringyouupassoonasIgettoNewYork. Iwilltellhimeverythingwhenhecomesback. Hewon’tbelieveituntilheseesitwithhisowneyes. (3)在带有till或until引导的时间状语从句的主从复合句里,如果主句用肯定式,其含义是“一直到……时”,谓语动词只能用延续性动词。如果主句用否定式,其含义是“直到……才……”,“在……以前不……”,谓语动词可用瞬间动词。例如: Theyoungmanreadtillthelightwentout. Let’swaituntiltherainstops. Wewon’tstartuntilBobcomes. Don’tgetoffuntilthebusstops. 2.条件状语从句 (1)条件状语从句通常由if,unless引导。例如: Whatshallwedoifitsnowstomorrow? Don’tleavethebuildingunlessItellyouto. (2)在条件状语从句里,谓语动词通常用现在时态表示将来的动作或状态。例如: I’llhelpyouwithyourEnglishifamfreetomorrow. Hewon’tbelateunlessheisill. (3)“祈使句and(or)陈述句”在意思上相当于一个带有条件状语从句的复合句。例如: Hurryup,oryou’llbelate. =Ifyoudon’thurryup,you’llbelate. Studyhardandyouwillpasstheexam. =Ifyoustudyhard,youwillpasstheexam. 3.原因状语从句 (1)原因状语从句通常由because,since,as引导。例如: Hedidn’tcometoschoolbecausehewasill. Asitisraining,weshallnotgothezoo. Sinceyoucan’tanswerthequestion,I’llasksomeoneelse. (2)because表示直接原因,语气最强。Because引导的原因状语从句多放在主句之后。回答由why提出的问题,只能用because。As和since语气较弱,一般用来表示明显的原因。由as和since引导的原因状语从居多放在句首。例如: ------Whyaren’tgoingthere? ------BecauseIdon’twantto. Ashehasnocar,hecan’tgetthereeasily. Sincewehavenomoney,wecan’tbuyit. (3)because和so不能同用在一个句子里。 (责任编辑:admin) |