初中英语语法动词八种时态详解 9页

初中英语八种时态归纳复习时态是英语学习中一个至关重要的内容，广大初中学生在实际运用时，往往对时态问题倍感棘手，下面我们就归纳复习一下这几种时态。一、一般现在时（一）定义表示经常性或习惯性的动作，或存在的状态，还表示主语具备的性格和能力及客观真理。例：Igetupat6:30inthemorning.Sheisathome.(二)构成主要用动词原形表示，当主语是第三人称单数时，在动词词尾加s/es。(三)句型1、肯定句：主语+谓语+其他。ShereadsEnglisheveryday.2、否定句：主语+don’t/doesn’t+谓语+其他。Hedoesn’tgetupat6:30inthemorning.3、一般疑问句：Do/Does+主语+V原+其他？DoyoulikeEnglish?Yes,Ido./No,Idon’t.4、特殊疑问句：特殊疑问词+do/does+主语+V原+其他？Whattimedoyougetupeverymorning?Wheredoesyourfatherwork?（四）时间状语Always,usually,often,sometimes,everyweek(day,year,month…),onceaweek(day,year,month…),onSundays,（五）用法1、表示经常性或习惯性的动作，或存在的状态，带与表示频率的时间状语如：often,sometimes,usually，always,everydayyear，month．．．）,once/twiceaweek(month,year,etc.),seldom,onSundays等连用。Ileavehomeforschoolatseveneverymorning.2、表示客观真理，科学事实、格言警句。Thesunrisesintheeast.日出东方。　　Theearthgoesaroundthesun.地球绕着太阳转。　　Tenminustwoiseight.十减二等于八。　　Lighttravelsfasterthansound.光的速度比声音的速度快。　　TheUnitedStatesliesbythewestcoastofthePacificOcean.美国位于太平洋西岸。3、根据英文语法规定，当主句的谓语动词是一般将来时，那么时间或条件状语从句的谓语动词只能用一般现在时来表示将来要发生的动作。　　I"lltellhimthenewswhenhecomesback.他回来时，我将告诉他这个消息。Ifyoucomethisafternoon,we’llhaveameeting.　　4、仅为了描述状态、性质、特征、能力等等。这里的目的是为了"描述现阶段的动作或状态"，其重点"不是强调动作发生的时间、或进行的状态"。例如：　　Hecanspeakfiveforeignlanguages.他能说五种外语。　　Thatisabeautifulcity.那是座美丽的城市。hydrogenoxidationsodiumsolution(about5%)intheandtojustismicro-alkaline,thenwithdistilledwaterdilutedtoscale,mixeduniform.thisliquidasintoHourestoresugarofstaymeasuringliquid.2.2.2titration:glucose,thesameoperation.2.2.3titration:accordingto3.8.3.2.3thesameoperation.2.3resultsofcalculationsandreducingsugarcontentafterconversion(13):X=(ax4000)÷(Vxm)(13)intheformula:X--contentofreducingsugarsinthesample(intermsofinvertsugar),%;A--Rhine-Edsugarscale(seetable5)foundthatreducingsugarconsumptioncoefficientofliquidinvertsugarcorrespondingtotheproducttobetested.F--concentrationoffehlingsolution;V--reducingsugarconsumptionbemeasuredbythetimedropsbyvolume,mL;M--samplemass,g.paralleltestresultsallowerrorsto0.5%.Sucrosecontentbytype(14):X=(A-B)x0.9(14):x--ofsucrosecontent,%;A--transformedthereducingsugarcontent,%;BeforeB--intothereducingsugarcontent,%.Note:incaseofdispute,thearbitrationlawofpotassiumferricyanidelaw.Ashhydroxymethylfurfuralby11.1reagentsandmaterials,exceptasotherwiseprovided,thereagentsarepure,todistilledwater.1.1.1barbituricacidsolution:weigh500mgbarbituricacidinabeakerofplus70mLdistilledwaterplacedonthehottubheatingmixingthesolution,cooledandmovedintothe100mLvolumetricflask, 　　ChangjiangRiverisoneofthelongestriversintheworld.长江是世界上最长的河流之一。　　Shemajorsinmusic.她主修音乐。　　Allmyfamilylovefootball.我全家人都喜欢足球。　　Mysisterisalwaysreadytohelpothers.我妹妹总是乐于助人。（四）动词第三人称单数形式变化规则1、一般情况下，动词后直接加-s;如：help-helps,clean-cleans,give-gives等。2、以s，x，ch，sh或o结尾的动词，在词尾加-es;如：dress-dresses,fix-fixes,watch-watches,finish-finishes等。3、以辅音字母加y结尾的动词，把y变为i，再加-es;如：study--studies,fly-flies,carry--carries等。4、动词have遇在主语是第三人称单数时，have改为has，如：Hehasaninterestingbook.5、动词be遇有主语是第一人称单数时，be改为am，遇有主语是第二人称时，be改为are，遇有主语是第三人称单数时，be改为is一、一般过去时（一）结构一般过去时用动词的过去式表示。基本结构否定句一般疑问句Be动词was/were+notwas或were提前，放于句首行为动词didn’t+do（动词原形）Did+主语+do（动词原形）注：在一般过去时的句子中，谓语动词可分为两类一类是be动词，其形式为was与第一、三人称单数连用，were与第二人称和复数人称的主语连用。凡是由be动词做谓语的句子，变否定句时，直接在其后加not,即wasn’t或weren’t，变一般疑问句将was/were放在句首，句末用问号。另一类谓语动词是由行为动词来充当，如stayedwentvisited等,这一类动词做谓语时，可与任何人称连用，句子变否定时，要在主语后面，动词的前面加didn’t，动词用原形；一般疑问句是把did提到句首，动词用原形。IwasinShanghailastyear.Iwasn’tinShanghailastyear.WasyouinShanghailastyear?Hewenttotheparkyesterday.Hedidn’tgototheparkyesterday?Didhegototheparkyesterday?（二）句式1、肯定句：主语+动词过去式+其他。IwasinBeijingyesterday.Iwenttothebeachyesterday.2、否定句：主语+wasn’t或weren’t+其他。主语+didn’t+V原+其他。Iwasn’tinBeijingyesterday.Ididn’tgotothebeachyesterday.hydrogenoxidationsodiumsolution(about5%)intheandtojustismicro-alkaline,thenwithdistilledwaterdilutedtoscale,mixeduniform.thisliquidasintoHourestoresugarofstaymeasuringliquid.2.2.2titration:glucose,thesameoperation.2.2.3titration:accordingto3.8.3.2.3thesameoperation.2.3resultsofcalculationsandreducingsugarcontentafterconversion(13):X=(ax4000)÷(Vxm)(13)intheformula:X--contentofreducingsugarsinthesample(intermsofinvertsugar),%;A--Rhine-Edsugarscale(seetable5)foundthatreducingsugarconsumptioncoefficientofliquidinvertsugarcorrespondingtotheproducttobetested.F--concentrationoffehlingsolution;V--reducingsugarconsumptionbemeasuredbythetimedropsbyvolume,mL;M--samplemass,g.paralleltestresultsallowerrorsto0.5%.Sucrosecontentbytype(14):X=(A-B)x0.9(14):x--ofsucrosecontent,%;A--transformedthereducingsugarcontent,%;BeforeB--intothereducingsugarcontent,%.Note:incaseofdispute,thearbitrationlawofpotassiumferricyanidelaw.Ashhydroxymethylfurfuralby11.1reagentsandmaterials,exceptasotherwiseprovided,thereagentsarepure,todistilledwater.1.1.1barbituricacidsolution:weigh500mgbarbituricacidinabeakerofplus70mLdistilledwaterplacedonthehottubheatingmixingthesolution,cooledandmovedintothe100mLvolumetricflask, 3、一般疑问句：was/were+主语+V原+其他？Did+主语+V原+其他？WereyouinBeijingyesterday?Didyougotothebeachyesterday?4、特殊疑问句：特殊疑问词+was/were+主语+其他？特殊疑问词+did+主语+V原+其他？Wherewereyouyesterday?Wheredidyougoyesterday?（三）时间状语ago,yesterday,thedaybeforeyesterday,lastweek,last(year,night,month…),in1989,justnow,attheageof5,oneday,longlongago,onceuponatime,etc.（四）用法1、表示过去某一时刻或某一段时间里所发生的动作或情况，常与明确的时间状语连用，如：yesterday,lastweek(month,year…),…ago,theotherday,justnow,attheageof…,in1980等连用。如：Attheageoften,shebegantolearntoplaythepiano.2、表示过去经常发生或反复发生的动作，常与表示频度的时间状语连用。WhenIwasachild,Ioftenplaythefootballinthestreet.3、在时间、条件状语从句中，常用一般过去时态代替过去将来时。Hesaidhewouldn’tgoifitrained.（五）动词过去式的规则变化1)一般情况下,在动词原形末尾加-ed;如look-looked2)结尾是字母e的动词加-d,如practice-practiced；3)结尾是“辅音字母+y”的动词,变“y”为“i”再加ed,如studystudied;4)重读闭音节结尾,双写动词尾的辅音字母，再加ed,如stopstopped。不规则动词表InfinitivePasttenseInfinitivePasttensecatchcaughtcomecamedodiddrawdrewdrinkdrankdrivedroveeatatefallfellamiswasarewerebeginbegunbreakbrokebringbroughtbuildbuiltbuyboughtcancould动词过去式的记忆口诀动词一般过去时,表示过去发生事；be用was或用were,have,has变had；谓语动词过去式,过去时间坐标志；一般动词加-ed,若是特殊得硬记。否定句很简单,主语之后didn’t添；疑问句也不难,did放在主语前；如果谓语之前有did,谓语动词需还原；动词若是was,were,否定就把not添。　三、一般将来时（一）概念表示将要发生的动作或存在的状态。hydrogenoxidationsodiumsolution(about5%)intheandtojustismicro-alkaline,thenwithdistilledwaterdilutedtoscale,mixeduniform.thisliquidasintoHourestoresugarofstaymeasuringliquid.2.2.2titration:glucose,thesameoperation.2.2.3titration:accordingto3.8.3.2.3thesameoperation.2.3resultsofcalculationsandreducingsugarcontentafterconversion(13):X=(ax4000)÷(Vxm)(13)intheformula:X--contentofreducingsugarsinthesample(intermsofinvertsugar),%;A--Rhine-Edsugarscale(seetable5)foundthatreducingsugarconsumptioncoefficientofliquidinvertsugarcorrespondingtotheproducttobetested.F--concentrationoffehlingsolution;V--reducingsugarconsumptionbemeasuredbythetimedropsbyvolume,mL;M--samplemass,g.paralleltestresultsallowerrorsto0.5%.Sucrosecontentbytype(14):X=(A-B)x0.9(14):x--ofsucrosecontent,%;A--transformedthereducingsugarcontent,%;BeforeB--intothereducingsugarcontent,%.Note:incaseofdispute,thearbitrationlawofpotassiumferricyanidelaw.Ashhydroxymethylfurfuralby11.1reagentsandmaterials,exceptasotherwiseprovided,thereagentsarepure,todistilledwater.1.1.1barbituricacidsolution:weigh500mgbarbituricacidinabeakerofplus70mLdistilledwaterplacedonthehottubheatingmixingthesolution,cooledandmovedintothe100mLvolumetricflask, TherewillbeanEnglishpartynextSaturday.Wewillcometoseeyoutomorrow.（二）结构1、由will+动词原形构成，其will适用于各种人称，与主语连在一起时，常常缩写为’ll。变否定句时，只需在will后加not，可缩写为won’t。在疑问句中，will需提前，构成will+主语+动词原形的结构。Hewillarriveherethisevening.他今晚抵达这里。2、shall+动词原形（常用于主语为第一人称）Ishall/willnotbefreetomorrow.我明天没空。3、begoingto+动词原形（打算、准备做某事）HeisgoingtospendhisholidaysinLondon.他打算在伦敦度假。（三）时间状语Tomorrow,nextday(week,month,year…),soon,inafewminutes,by…,thedayaftertomorrow,etc.（四）用法1、表示在将来某个时间将要发生的动作或存在的状态，常与表示将来的时间状语，如：tomorrow,nextday（week，month，year．．．．），thisevening(weekend…),inthefuture,inafewminutes，thedayaftertomorrow,by．．．，soon等连用。IwillpayavisittoShanghainextweek.Ihopeyouwon’tbelatenexttime.2、当主句为一般现在时，在以after,when,while,assoonas,if,unless等引导的时间或条件句中，要用一般现在时表将来。I’lldoitbetteriftheteachergivesmeanotherchance.四、过去将来时基本结构：主语+was/were+goingto+do+其他；主语+would/should+do+其他用法：　　表示过去的某时以后将要发生的动作。但这个"将来"时间绝不会延伸到“现在”；而仅限于“过去时间区域内”。由此可以看出，含这个时态的句子常带一个表示“过去某个时间点”的状语。这个状语或是一个短语，或是一个句子。这个时态常用于：　　A）宾语从句或间接引语中；B）表示过去习惯性的动作；C）表示过去情况中的“愿望”、“倾向”，多用于否定句。例如：　　A)WhenIthoughtaboutit,Iwonderedwhattheirreactionwouldbe.当我考虑这件事时，我想知道他们的反应是什么。　　ShetoldmethatshewouldgoontriptoEuropethenextday.她告诉我，她第二天要去欧洲旅行。　　Hedidn"texpectthatwewouldallbethere.他没料到我们会全在那儿。　　B)Duringthatperiod,hewoulddomorning-exerciseseveryday.在那段时间，他每天早锻炼。　　Wheneverhehadtime,hewouldhelphismotherwithsomehousework.无论他什么时间有空,他总是帮他妈妈干点家务活。　　C)Nomatterhowdifficulttheworkwas,hewouldkeepondoingituntilhehydrogenoxidationsodiumsolution(about5%)intheandtojustismicro-alkaline,thenwithdistilledwaterdilutedtoscale,mixeduniform.thisliquidasintoHourestoresugarofstaymeasuringliquid.2.2.2titration:glucose,thesameoperation.2.2.3titration:accordingto3.8.3.2.3thesameoperation.2.3resultsofcalculationsandreducingsugarcontentafterconversion(13):X=(ax4000)÷(Vxm)(13)intheformula:X--contentofreducingsugarsinthesample(intermsofinvertsugar),%;A--Rhine-Edsugarscale(seetable5)foundthatreducingsugarconsumptioncoefficientofliquidinvertsugarcorrespondingtotheproducttobetested.F--concentrationoffehlingsolution;V--reducingsugarconsumptionbemeasuredbythetimedropsbyvolume,mL;M--samplemass,g.paralleltestresultsallowerrorsto0.5%.Sucrosecontentbytype(14):X=(A-B)x0.9(14):x--ofsucrosecontent,%;A--transformedthereducingsugarcontent,%;BeforeB--intothereducingsugarcontent,%.Note:incaseofdispute,thearbitrationlawofpotassiumferricyanidelaw.Ashhydroxymethylfurfuralby11.1reagentsandmaterials,exceptasotherwiseprovided,thereagentsarepure,todistilledwater.1.1.1barbituricacidsolution:weigh500mgbarbituricacidinabeakerofplus70mLdistilledwaterplacedonthehottubheatingmixingthesolution,cooledandmovedintothe100mLvolumetricflask, accomplishedit.不管工作有多难，他总会坚持不懈地把它干完。　　Theyknewthatwewouldneverpermitsuchathing.他们知道我们绝不会允许发生这样的事。　　Evenafterthelectureended,theaudiencewouldnotleave.甚至在讲座结束之后，听众仍不肯离去。 过去将来时基本结构　　过去将来时由would,was/weregoingto,was/weretowas/wereaboutto等加动词原形构成,也可由was/wereonthepointof加动名词构成。　　例句：　　Iknewyouwouldagree.我知道你会同意的。IsaidIwouldarrangeeverything.我说我来安排一切。 时间状语：Thenextday(morning,year…),thefollowingmonth(week…),etc.五、现在进行时（一）结构由Be(am／is／are)＋动词—ing构成。（二）用法1、表示说话时刻正在进行的动作及行为，或者包括说话时刻在内的一段时间正在进行的动作。常用时间状语及标志词：now(atthemoment),listen,look,thisweek,thisevening,thesedays等。Listen,Someoneisplayingthepianointhenextroom.2、表示一种渐进的过程。MyyoungerbrotherisbecomingmoreandmoreinsterestedinEnglish.3、与always,allthetime,forever等连用，表示说话人某种强烈的情感，如：赞许、批评；喜欢、厌恶等。例如：　　Heisalwaysthinkingofothers,notofhimself.（表示赞许）他总是为他人着想，而不为自己。　　Sheisoftendoingwellatschool.（表示满意）她在学校学习挺不错的。　　Areyoufeelingbettertoday?（表示亲切）你今天觉得好一些吗？　　Oneofmyroommatesisconstantlyleavingthingsabout.（表示不满）我的一个室友老是乱扔东西。　　Somesellersareoftenknockingatourdoorandpromotingtheirproductstous.（表示不喜欢）有些推销员老是敲我家的门,向我们推销他们的产品。4、表示移位的动词，如go,come,leave,start,arrive等，其现在进行时可表将来。SheisleavingforBeijingnextweak.Myfriendiscomingfordinner.（三）句型1、肯定句：主语+be(am／is／are)＋动词—ing+其他。Iamstudyingnow.2、否定句：主语+be+not+动词—ing+其他。Iamnotstudyingnow.3、一般疑问句：Be+主语+动词—ing+其他？Isshestudyingnow?Yes,sheis./No,sheisn’t.hydrogenoxidationsodiumsolution(about5%)intheandtojustismicro-alkaline,thenwithdistilledwaterdilutedtoscale,mixeduniform.thisliquidasintoHourestoresugarofstaymeasuringliquid.2.2.2titration:glucose,thesameoperation.2.2.3titration:accordingto3.8.3.2.3thesameoperation.2.3resultsofcalculationsandreducingsugarcontentafterconversion(13):X=(ax4000)÷(Vxm)(13)intheformula:X--contentofreducingsugarsinthesample(intermsofinvertsugar),%;A--Rhine-Edsugarscale(seetable5)foundthatreducingsugarconsumptioncoefficientofliquidinvertsugarcorrespondingtotheproducttobetested.F--concentrationoffehlingsolution;V--reducingsugarconsumptionbemeasuredbythetimedropsbyvolume,mL;M--samplemass,g.paralleltestresultsallowerrorsto0.5%.Sucrosecontentbytype(14):X=(A-B)x0.9(14):x--ofsucrosecontent,%;A--transformedthereducingsugarcontent,%;BeforeB--intothereducingsugarcontent,%.Note:incaseofdispute,thearbitrationlawofpotassiumferricyanidelaw.Ashhydroxymethylfurfuralby11.1reagentsandmaterials,exceptasotherwiseprovided,thereagentsarepure,todistilledwater.1.1.1barbituricacidsolution:weigh500mgbarbituricacidinabeakerofplus70mLdistilledwaterplacedonthehottubheatingmixingthesolution,cooledandmovedintothe100mLvolumetricflask, 4、特殊疑问句：特殊疑问词+Be+主语+动词—ing+其他？Whatareyoudoingnow?（四）时间状语Now,atthistime,days,etc.look.listen（五）动词的现在分词形式构成的几种方法：1、一般在动词原形结尾直接加-ing。read-reading，go-going，visit-visiting 2、以不发音字母e结尾的动词，去e再加-ing。live-living,write-writing，make-making,take-taking3、 以重读闭音节结尾且末尾只有一个辅音字母的词，双写这个字母再加-ing。sit-sitting,begin-beginning,get-getting,run-running,put-putting 4、少数几个以ie结尾的动词，变ie为y再加-ing。die-dying,lie-lying,tie-tying六、过去进行时（一）结构由was/were+动词-ing构成。（二）用法表示过去某一时刻或某一段时间正在进行或发生的动作。动作发生的特指时间常用一个短语或时间状语从句来表明，如：atthistimeyesterday，at7:00yesterday，lastnight,fromseventonine,atthattime以when或while引导的时间状语从句等。MyfamilywerewatchingTVatthistimeyesterday.注意：（1）以when引导的时间状语从句中，从句动作，主句用过去进行时，表示一个动作发生时，另一个动作正在进行。Whenhecalledme,Iwashavingdinner.（2）以while引导的时间状语从句中，从句与主句的动作在过去某一时刻同时进行，while常译为“当……的时候，同时”。TomwasdoinghishmeworkwhilehiesisterwaswatchingTV.　（三）时间状语atthistimeyesterday,atthattime或以when引导的谓语动词是一般过去时的时间状语等。七、现在完成时（一）含义现在完成时用来表示现在之前已发生或完成的动作或状态，但其结果却和现在有联系,也就是说,动作或状态发生在过去但它的影响现在还存在。e.g.Ihavelostmywallet.(含义是：现在我没有钱花了。)Janehaslaidthetable.(含义是：已可以吃饭了。)Michaelhasbeenill.(含义是：现在仍然很虚弱。)Hehasreturnedfromabroad.(含义是：现在已在此地)（二）结构助动词have/has+动词过去分词，主语为第三人称单数用has，其他人称用have。（三）句型hydrogenoxidationsodiumsolution(about5%)intheandtojustismicro-alkaline,thenwithdistilledwaterdilutedtoscale,mixeduniform.thisliquidasintoHourestoresugarofstaymeasuringliquid.2.2.2titration:glucose,thesameoperation.2.2.3titration:accordingto3.8.3.2.3thesameoperation.2.3resultsofcalculationsandreducingsugarcontentafterconversion(13):X=(ax4000)÷(Vxm)(13)intheformula:X--contentofreducingsugarsinthesample(intermsofinvertsugar),%;A--Rhine-Edsugarscale(seetable5)foundthatreducingsugarconsumptioncoefficientofliquidinvertsugarcorrespondingtotheproducttobetested.F--concentrationoffehlingsolution;V--reducingsugarconsumptionbemeasuredbythetimedropsbyvolume,mL;M--samplemass,g.paralleltestresultsallowerrorsto0.5%.Sucrosecontentbytype(14):X=(A-B)x0.9(14):x--ofsucrosecontent,%;A--transformedthereducingsugarcontent,%;BeforeB--intothereducingsugarcontent,%.Note:incaseofdispute,thearbitrationlawofpotassiumferricyanidelaw.Ashhydroxymethylfurfuralby11.1reagentsandmaterials,exceptasotherwiseprovided,thereagentsarepure,todistilledwater.1.1.1barbituricacidsolution:weigh500mgbarbituricacidinabeakerofplus70mLdistilledwaterplacedonthehottubheatingmixingthesolution,cooledandmovedintothe100mLvolumetricflask, 1、肯定句：主语+have/has+动词过去分词+其他。IhavestudiedEnglishfor5years.2、否定句：主语+have/has+not+动词过去分词+其他。Wehaven’tbeenthere.3、一般疑问句：Have/Has+主语+动词过去分词+其他？Hasheeatenthatapple?4、特殊疑问句：特殊疑问词+have/has+主语+动词过去分词+其他？（四）时间状语yet,already,just,never,ever,sofar,bynow,since+时间点，for+时间段，recently,lately,inthepastfewyears,etc.（五）用法1、现在完成时可以用来表示发生在过去某一时刻的、持续到现在的情况,常与for,since连用。e.g.Maryhasbeenillforthreedays.Ihavelivedheresince1998.2、现在完成时往往同表示不确定的过去时间状语连用,如already,yet,just,before,recently,lately等：e.g.Hehasalreadyobtainedascholarship.Ihaven’tseenmuchofhimrecently(lately).Wehaveseenthatfilmbefore.Havetheyfoundthemissingchildyet?3、现在完成时常常与表示频度的时间状语连用，如often,sometimes,ever,never,twice,onseveraloccasion等：e.g.HaveyoueverbeentoBeijing?IhaveneverheardBunnysayanythingagainsther.Ihaveusedthispenonlythreetimes.Itisstillgood.Georgehasmetthatgentlemanonseveraloccasions.4、现在完成时还往往可以同包括现在时间在内的时间状语连用，如now,uptothesefewdays/weeks/months/years,thismorning/week/month/year,now,just,today,uptopresent,sofar等。e.g.Peterhaswrittensixpaperssofar.Manhasnowlearnedtoreleaseenergyfromthenucleusoftheatom.Therehasbeetoomuchrainthisyear.Therelationsbetweenushavebeenenhancedinthepastfewyears.Uptothepresenteverythinghasbeensuccessful.5、现在完成时表示现在之前就已完成的动作,虽然其效果或影响仍然存在但已不再继续,但是有一些现在完成时的句子，在后面加上for+一段时间，则现在完成时的动作就表示延续性。e.g.ThomashasstudiedRussian.(现在不再学俄语)ThomashasstudiedRussianforthreeyears.(=ThomasbegantostudyRussianthreeyearsago,andisstillstudyingitnow.)6、现在完成时还可以用来表示过去的一个时间到现在这段时间内重复发生的动作。e.g.Wehavehadfourtextsthissemester.hydrogenoxidationsodiumsolution(about5%)intheandtojustismicro-alkaline,thenwithdistilledwaterdilutedtoscale,mixeduniform.thisliquidasintoHourestoresugarofstaymeasuringliquid.2.2.2titration:glucose,thesameoperation.2.2.3titration:accordingto3.8.3.2.3thesameoperation.2.3resultsofcalculationsandreducingsugarcontentafterconversion(13):X=(ax4000)÷(Vxm)(13)intheformula:X--contentofreducingsugarsinthesample(intermsofinvertsugar),%;A--Rhine-Edsugarscale(seetable5)foundthatreducingsugarconsumptioncoefficientofliquidinvertsugarcorrespondingtotheproducttobetested.F--concentrationoffehlingsolution;V--reducingsugarconsumptionbemeasuredbythetimedropsbyvolume,mL;M--samplemass,g.paralleltestresultsallowerrorsto0.5%.Sucrosecontentbytype(14):X=(A-B)x0.9(14):x--ofsucrosecontent,%;A--transformedthereducingsugarcontent,%;BeforeB--intothereducingsugarcontent,%.Note:incaseofdispute,thearbitrationlawofpotassiumferricyanidelaw.Ashhydroxymethylfurfuralby11.1reagentsandmaterials,exceptasotherwiseprovided,thereagentsarepure,todistilledwater.1.1.1barbituricacidsolution:weigh500mgbarbituricacidinabeakerofplus70mLdistilledwaterplacedonthehottubheatingmixingthesolution,cooledandmovedintothe100mLvolumetricflask, 现在完成时中的时间状语：★already通常用于肯定句中，意为“已经”，位于行为动词之前,be动词、助动词之后。有时可放在疑问句句尾，表示惊讶。例如：Wehavealreadycleanedtheclassroom.Haveyoufinisheditalready？★yet用于疑问句中表示“已经”；用于否定句中，表示“还(没)”。例如：—Hashefoundhiswatchyet？他还没找到他的表吗？—No,notyet.是,还没有。★ever意为“曾经”，常用于疑问句或否定句中，位于助动词和过去分词之间，表示从过去到目前为止的时间。例如：Haveyoueverbeenthere？你曾经去过那里吗？Nothinghaseverhappenedhere.这里未曾发生过什么事。★never意为“（曾经）从未、没有”,是否定副词，在句中位于助动词和过去分词之间。ever与否定词not连用相当于never。例如：Ihaven’teverspokentoher.=Ihaveneverspokentoher.我从未跟她讲过话。★just意为“刚刚”,用于现在完成时,表示行为刚刚过去,位于助动词与过去分词之间。e.g.Hehasjustcomebackfromschool.他刚从学校回来。★justnow意为“刚才”,表示过去某时,用于一般过去时,位于句首或句尾均可。e.g.Hecamefromschooljustnow.他刚才从学校回来。★for和since的用法及区别。for与一段时间连用，since与时间点连用。注意：since后接过去时的时间状语或过去时的句子。e.g.IhavebeentoShanghaitwicesince1970.Ihaven’tseenhersincesheleftShanghai.IsawPingPingsixyearsago.SinceIhaveneverseenher.★have/hasgoneto、have/hasbeento和have/hasbeenin的区别。have/hasgoneto去了,在去某地的路上或在某地,人还未回来have/hasbeento曾经去过,人已经回来了have/hasbeenin已经在,常与一段时间连用e.g.ShehasbeentoShanghaibefore.她以前曾去过上海。ShehasbeeninShanghaifortenyears.她在上海10年了。HashegonetoQingdao?他去青岛了吗？但不能说HaveyougonetoQingdao?一般过去时与现在完成时的转换在现在完成时中，延续性动词能与表示一段时间的状语连用，瞬间动词却不能。但是，可用别的表达方式：①瞬间动词用于“一段时间+ago”的一般过去时的句型中；②瞬间动词可改成与之相对应的延续性动词及短语，与一段时间连用；③瞬间动词用于“Itis+一段时间+since+一般过去时”的句型中，表示“自从……以来有……时间”的意思，主句一般用itis来代替Ithasbeen;④瞬间动词用于“Sometimehaspassedsince+一般过去时”的句型中。请看：A.HejoinedtheLeaguetwoyearsago.B.HehasbeenintheLeaguefortwoyears.hydrogenoxidationsodiumsolution(about5%)intheandtojustismicro-alkaline,thenwithdistilledwaterdilutedtoscale,mixeduniform.thisliquidasintoHourestoresugarofstaymeasuringliquid.2.2.2titration:glucose,thesameoperation.2.2.3titration:accordingto3.8.3.2.3thesameoperation.2.3resultsofcalculationsandreducingsugarcontentafterconversion(13):X=(ax4000)÷(Vxm)(13)intheformula:X--contentofreducingsugarsinthesample(intermsofinvertsugar),%;A--Rhine-Edsugarscale(seetable5)foundthatreducingsugarconsumptioncoefficientofliquidinvertsugarcorrespondingtotheproducttobetested.F--concentrationoffehlingsolution;V--reducingsugarconsumptionbemeasuredbythetimedropsbyvolume,mL;M--samplemass,g.paralleltestresultsallowerrorsto0.5%.Sucrosecontentbytype(14):X=(A-B)x0.9(14):x--ofsucrosecontent,%;A--transformedthereducingsugarcontent,%;BeforeB--intothereducingsugarcontent,%.Note:incaseofdispute,thearbitrationlawofpotassiumferricyanidelaw.Ashhydroxymethylfurfuralby11.1reagentsandmaterials,exceptasotherwiseprovided,thereagentsarepure,todistilledwater.1.1.1barbituricacidsolution:weigh500mgbarbituricacidinabeakerofplus70mLdistilledwaterplacedonthehottubheatingmixingthesolution,cooledandmovedintothe100mLvolumetricflask, C.ItistwoyearssincehejoinedtheLeague.D.TwoyearshaspassedsincehejoinedtheLeague.八、过去完成时（一）过去完成时的概念过去完成时表示过去某一时间或某一事件之前已经发生的动作或状态，即过去的过去。图示如下：　----|--------------------------|---------------------------|----------------------->　过去完成　        过去              现在　　　　　　将来（二）构成1、肯定句：主语+had＋过去分词Whenwegotthere,thefootballmatchhadalreadystarted.2、否定句：主语+hadnot+过去分词Hehadn’tworkedfortwoyearsbythen.3、疑问句：had+主语+过去分词…？Hadhefinishedtheworkbylastmonth?（三）时间状语Before,bytheendoflastyear(term,month…),etc.（四）用法1、过去完成时表示过去某一时刻或者某一动作之前完成的动作或状态;句中常用by,before,until,when等词引导的时间状语。e.g.Bythetimeshegotup,herbrotherhadalreadygoneintothebathroom.2、过去完成时的动词还可以表示过去某一时刻之前发生的动作或者状态持续到过去某个时间或者持续下去。例如：Beforeheslept,hehadworkedfor12hours.　3、在told,said,knew,heard,thought等动词后的宾语从句。例如：Shesaid(that)shehadneverbeentoParis.4、在过去不同时间发生的两个动作中，发生在先，用过去完成时；发生在后，用一般过去时。例如：Whenthepolicearrived,thethieveshadrunaway.5、bythetime“直到……时候”。指从过去某一点到从句所示的时间为止的一段时间。如：Bythetimewegottohishouse,hehadfinishedsupper.6、表示意向的动词,如hope,wish,expect,think,intend,mean,suppose等,用过去完成时表示“原本…，未能…”。例如：Wehadhopedthatyouwouldcome,butyoudidn"t.针对性练习：（见课后资料）hydrogenoxidationsodiumsolution(about5%)intheandtojustismicro-alkaline,thenwithdistilledwaterdilutedtoscale,mixeduniform.thisliquidasintoHourestoresugarofstaymeasuringliquid.2.2.2titration:glucose,thesameoperation.2.2.3titration:accordingto3.8.3.2.3thesameoperation.2.3resultsofcalculationsandreducingsugarcontentafterconversion(13):X=(ax4000)÷(Vxm)(13)intheformula:X--contentofreducingsugarsinthesample(intermsofinvertsugar),%;A--Rhine-Edsugarscale(seetable5)foundthatreducingsugarconsumptioncoefficientofliquidinvertsugarcorrespondingtotheproducttobetested.F--concentrationoffehlingsolution;V--reducingsugarconsumptionbemeasuredbythetimedropsbyvolume,mL;M--samplemass,g.paralleltestresultsallowerrorsto0.5%.Sucrosecontentbytype(14):X=(A-B)x0.9(14):x--ofsucrosecontent,%;A--transformedthereducingsugarcontent,%;BeforeB--intothereducingsugarcontent,%.Note:incaseofdispute,thearbitrationlawofpotassiumferricyanidelaw.Ashhydroxymethylfurfuralby11.1reagentsandmaterials,exceptasotherwiseprovided,thereagentsarepure,todistilledwater.1.1.1barbituricacidsolution:weigh500mgbarbituricacidinabeakerofplus70mLdistilledwaterplacedonthehottubheatingmixingthesolution,cooledandmovedintothe100mLvolumetricflask,