时间状语从句和省略

时间状语从句和省略一、时间状语从句1.某些易用错的连词。(1)连词immediately/directly/instantly和词组themoment,theminute意为“一……就……”，相当于assoonas。如：Thethiefranawaythemoment/directlyhesawthepoliceman.[注意]a.immediately/directly/instantly也是副词，在句中作状语。如：Ididn’timmediatelyrealizehowseriousthesituationwas.b.介词on/upon+名词/V-ing也表示“一……就……”。如：YaoMingwassurroundedbythemediaonhisarrivalattheairport.OnseeingthepaintingbyVanGogh,Ifellinlovewithitatonce.(2)词组thefirsttime,thelasttime,eachtime,everytime以及bythetime，都引导时间状语从句。如：ThefirsttimeIspokeEnglishbeforeforeigners,Iwasastudentofhighschool.EverytimeImeetthepolicemanatthatcrossroads,hewillgivemeabigsmile.[注意]forthefirsttime是介词短语，意为“第一次……”，常用来作状语。Theyhadaface-to-facetalkforthefirsttime.(3)when,while和as引导时间状语从句的区别：when引导时间状语从句时，可与短暂性动词连用，也可与延续性动词连用；而while只能与延续性动词连用；as表示两个动作的同时性，意为“一边……，一边……”。如：WhenIenteredtheclassroom,allthestudentslookedupatmecuriously.CouldyoulookafterRobertwhileIampreparingthereport?Thechildrensangastheyclimbedthemountain.2.时间状语从句中的时态。(1)when,assoonas,everytime,immediately,themoment等在引导时间状语从句时，若从句用一般现在时，主句用一般将来时。如：ThemomentIfinishmyhomework,Iwillgoouttoplayfootball.(2)在It/This/Thatisthefirst/second/lasttimethat…中，that从句中的谓语动词用现在完成时；而It/This/Thatwasthefirst/second/lasttimethat…中，that从句中的谓语动词用过去完成时。如：ThisisthefirsttimethatIhavevisitedtheGreatWall.Thatwasthesecondtimethathehadbeeninterruptedbythenoiseoutside.二、省略1.状语从句中的省略。(1)连词when,while,if,as,though/although,until,once,whether,unless,where等引导的状语从句中，当主句的主语和从句的主语一致时，常省略跟主句相同的主语和be，只剩下主要的部分。如：While/When(youare)crossingthestreet,youmustbecareful.Unless(Iam)invitedtoattendtheparty,Iwon’tgotohishouse.(2)当出现when,if,where,wherever,whenever,than等后直接接possible,necessary时，可理解为省略了“it+be的适当形式”。类似的还有：ifso,ifnot,ifsome,ifany,ifever等。如：Pleasecallmeupif(itis)necessary.Irelaxwithagoodbookwhenever(itis)possible.2.不定式结构中的省略。在同一个句子或紧密联系的对话中，为了避免重复，作宾语或补足语的不定式再次出现时，不定式符号后面的内容常被省略，只保留不定式符号。常用于refuse,wouldlike/love,wish,want,mean,expect,hope,intend以及afraid,happy,glad,willing,ready等后。如：Susan’sparentsdidn’tallowhertotravelaloneinTibet,butshestillhopedto(travelaloneinTibet).[注意]当to后是be或have时，be与have不能省略。如：—IsMissYangadoctor?—No,butsheusedtobe(adoctor).—Ihaven’thandedinmyhomeworkyet.—Well,yououghttohave(handedinyourhomework).3.可以用so,not来替代上文或问句中的一部分或整个句子。think,believe,guess,suppose,hope等有这样的用法。如：—Canyoufinishthetaskaheadoftime?—Ithinkso./Ithinknot./Idon’tthinkso.4.当不定式作表语时，若主句中出现do的各种形式，to可以省略。如：Whatweshoulddoabouttheproblemis(to)leaveitalone.[注意]在havenochoicebuttodo…句型中，to不省略，但若有do的各种形式，to可以省略。如：Theyhadnochoicebuttowaitforthepolicetocome.Thechilddoesnothingbutplayallday.【巩固练习】1.______LangLangwasinhistwenties,hehadbeenawell-knownpianistathomeandabroad.A.AssoonasB.EachtimeC.ForthefirsttimeD.Bythetime2.Howlongdoyouthinkitwillbe______thecomputercompanycandevelopthehouseholdrobot?A.sinceB.beforeC.unlessD.that3.—HaveyougotanyplansforthecomingChristmasholiday?—Yes.______,I’mgoingtovisitChina.A.IfnotB.IfnecessaryC.IfpossibleD.Ifso