人教版（2019）必修 第三册Unit 4 Space exploration-Period 3 Discovering Useful Structure课件(共19张PPT).pptVIP

Period3DiscoveringUsefulStructuresUnit4SpaceExploration1.Toknowthebasicrulesoftheinfinitive2.TouseitflexiblyindifferentcontextsLearningaimsLeading-inDuetotheCOVID-19epidemic,expertsadviseus________(stay)athome.However,tolearnonlineisnotsopleasant.First,Ifindithard________(follow)myteachers.What’sworse,Istillhavealotofhomework______(do).Totellthetruth,sometimesIfail____________(handin).Thankstomyclassmates,thegroupleaderinparticular,theyalwaysremindme________(finish)myhomeworkontime.Gradually,mystudyseems______________(get)better.Nowmygoalis________(be)atopstudentinmyclass.Whatdoyouthinkofonlinelearning?tostaytofollowtohanditintofinishtobegettingtobetodo动词不定式由“to+动词原形”构成，to是不定式标志，无意义，有时可省略。不定式既有名词、形容词或副词的某些语法功能，又有动词的时态和语态的特点及作用,但不能作谓语。考点一:不定式的时态和语态Grammar：Infinitive主动语态被动语态意义一般时todotobedone表示动词与谓语动作同时发生或发生在谓语动词之后完成时tohavedonetohavebeendone表示动作发生在谓语动词之前进行时tobedoing表示谓语动词发生时，不定式的动作正在进行完成进行时tohavebeendoing表示动作发生在谓语动词之前且一直持续到谓语动词发生时仍在进行【即学即练】1.Imsorry_______________(keep)youwaitingsolong.3.Heisthought______________(write)thebooktenyearsago.tohavekepttohavewritten2.Sheistooyoung___________(attend)school.toattend4.Theproblemremains_____________(settle).tobesettled5.Shepretended______________(study)Englishwhenhermomcamein.tobestudying动词不定式具有名词，形容词和副词的特性动词不定式不能作谓语，是非谓语的一种形式。主语、宾语，表语定语、表语，补足语状语考点二：不定式在句中的作用不定式作主语※Toseeistobelieve.Iwon’tbelieveituntilIseeitwithmyowneyes.※Beingexposedtothenoisysurroundingsforalongtimemayresultinsomephysicalandmentalproblems.A不定式作主语一般表示具体的,将来的,有意识的动作.动词-ing作主语表示抽象的,无意识的,习惯性的倾向.B单个不定式作主语时谓语动词用单数。两个或两个以上的不定式做主语时，谓语动词常用复数形式；但当它们作为一个整体时，谓语动词用单数。※Toloveandtobelovedissweettous.※Toimprovepeople’slivesa