译林版（2020）必修第二册Unit 3 Festivals and Customs Grammar and usage 虚拟语气课件

UnrealConditionals非真实条件虚拟语气Ifyouenjoyscubadivingorsnorkeling,theCaribbeanandtheSouthPacificSeasarewonderfulplacestovisit.Ifyouvisittheseplaces,youwillfindbeautifulcoralreefsfullofavarietyofoceanlife.Coralisalivingcreaturethatcanbehardorsoft.Coralreefsareformedbysmallcreaturescalledcoralpolyps.Whenthecoralpolypstakecalciumfromseawater,theycanturnthecalciumintolimestoneshelters.Acoralreefisformedifseveralcoloniesofcoralpolypsworktogethertocreatealargehome.Ifyouenjoyscubadivingorsnorkeling,thesearewonderfulplacestovisit.Realconditionstalkaboutrealsituations,suchasfactsandregularlyoccurringevents.Ifyouvisit,youwillfindbeautifulcoralreefsfullofavarietyofoceanlife.RealinthepresentRealinthefutureIftherewerenocoralreefs,severalspecieswouldnotexist.Eventhoughcoralreefscoverlessthanonepercentoftheearth’ssurface,theyprovideahometoabout25%ofallmarinelife.Withouttheprotectionandcoverofcoralreefs,animalslikeoysters,clams,grouperandsnapperwoulddie.Theseanimalsareimportantsourcesoffoodforotheranimals.Ifthereefsdied,otherecosystemswouldalsodie.Iftherewerenocoralreefs,severalspecieswouldnot

exist.

Unrealconditionstalkaboutimaginaryorimpossiblesituations.Ifthereefsdied,otherecosystemswould

alsodie.UnrealinthepresentorfutureNote:Wereisusedforbothsingularandpluralsubjects.Infact,manycoralreefshavebeendyinginrecentyears.Thisprocessisknownasbleaching.Bleachedcoralreefsfirstturnwhiteandthenbecomedeadbrowncoral.Sadly,someofthedamagecouldhavebeenavoidedifmorepeoplehadbeenawareofthenegativeeffectsofhumanactivitysuchaspollutionandover-fishing.Manyexpertsagreethatmuchofthedamageweseetodaywouldhavebeenprevented

iftherehadbeenagreaterefforttoeducatethepublicaboutthefragilereefecosystem.7Inunrealconditionsinthepast,wouldexpressesadesiredorpredictableresult.Couldexpressesapossibleoption.Muchofthedamagewouldhavebeenprevented

iftherehadbeenbettereducation.Someofthedamagecouldhavebeenavoidedifmorepeoplehadbeenawareofthenegativeeffectsofpollution.Climatechangeisamajorreasonforthedeteriorationofcoralreefs.Iftheoceantemperatureswerenotsteadilyrising,thecoralreefswouldbe

healthier.Whenwateristoowarm,

coralsexpelthealgaelivingintheirtissues.Thiscausesthe

coral

toturncompletelywhite.Coralscansometimessurvivebleaching,buttheyareweakerandundermorestress.Theoceantemperaturesarerising.Coralreefsarenothealthy.

Progressiveverbformsareusedinprogressivesituations.Iftheoceantemperatureswerenotrising,coralreefswouldbehealthier.Realsituation:ConditionalStatement:Climatechangeisnottheonlyproblem.Trashoftenendsupinthesea.Theseitemscanentangleandkillreeforganismsandbreakordamagereefs.Plasticsareespeciallyhardonoceanlife.Hadtheeffectsofplasticsonmarinelifebeenbetterunderstood,wecouldhavefoundalternativestoplasticsooner.Conservationistsareworkinghardtocleanupourseas.Otherwise,theproblemwouldbemuchworse.However,inordertotrulyaddresstheproblem,weneedtoreducetheamountofplasticweuseandthrowaway.Hadweknown,wecouldhavepreventedtheproblem.

Withwereandhad(pastperfect),andshould,sometimesifisomitted,andthesubjectandverbareinverted.Weremorepeopleawareoftheproblem,therewouldbegreaterprogress.Hadweknown=IfwehadknownWeremorepeopleaware=IfmorepeoplewereawareTheyareworkingtofindasolution.Otherwise,theproblemwouldbemuchworse.

Oftentheif-clauseisimplied,notstated.Conditionalverbsarefrequentlyusedfollowingotherwise.Iftheyweren’tworkingtofindasolutionImpliedcondition:1.Whatwouldhappeniftherewerenocoralreefs?2.Whatwouldyoudoifyouhadachancetosavethecoralreefs?3.Ifyouwereabletotravelanywhereintheworld,wherewouldyougo?4.Thinkaboutaregretoramistakeyou’vemade.Whatcouldyouhavedonedifferently?PRACTICE1–AskYourPartnerPRACTICE2Completethesentencewiththeverbsinparentheses.1.IfIcouldtravelanywhereintheworld,I(go)_________________totheGreatBarrierReefinAustralia.2.I(travel)________________________therelastyearifIhadhadenoughmoney.3.Janewouldtryscubadivingi