2016年译林牛津版英语必修二Unit1 Tales of the unexplained Grammar and usuageppt课件.ppt

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1、Unit1Presentperfecttense&PresentprefectcontinuoustenseGrammarLead-inLookatthefollowingsentencesandtrytoexplainwhythetenseisusedinthesesentences.1.WehavestudiedEnglishforaboutfiveyears.2.Theyhavelivedtheresince1990.3.Shehasn’tfinishedherhomeworkyet.4.

2、Erichasjustcomeback.5.Howlonghaveyoubeenhere?1.Theformofthepresentperfecttense:Weformthepresentperfecttensewithhave/hasandthepastparticipleoftheverb.have(has)+过去分词Justinhasdisappeared,soKellyisverysad.Weusethepresentperfecttensetotalkaboutthingsthath

3、appenedintherecentpast,butareconnectedtothepresent.Note:2.Theusesofthepresentperfecttense:IhavenotseenJustinsincelastFridaynight.Wealsousethepresentperfecttensetotalkaboutsomethingthatstartedinthepastandisstillhappeningnow.Note:Ihaven’tseenyourforage

4、s.Hehasjustgoneout.Ithasbeenverycoldlately.Shehasalreadyfinishedherhomework.Hehasn’tseenhersincethemeeting.Note:Weusethepresentperfecttensewhentheexacttimeofanactionisnotclearorimportant.Weuseitwithtimeexpressionssuchas:alreadyeverforjustlatelyneverr

5、ecentlysinceyetWeusealreadyforaffirmativestatements,yetfornegativestatements.Weusefor+aperiodoftime,since+apointintime.Note:Weusethepresentperfecttensetotalkaboutactionsthatwerecompletedonlyashorttimeago.Hehasjustgoneout.(=Hewentoutafewminutesago.)Ih

6、avejustheardthenews.(=NowIknowthenews.)Note:Wecanalsousethepresentperfecttenseforrepeatedactions,thatis,weusethepresentperfecttensewiththetimeexpressionsonce/twice/threetimes…TheysaythattheyhavebeentoAmericamanytimes.Lookatthesentencesandfindthediffe

7、rence:Tomhasrungupthreetimesthismorning.Nowitisstillinthemorning.Tomrangupthreetimesthismorning.Nowitisnotstillinthemorning.Actionsoccurringinanincompleteperiodmightbeindicatedbytodayorthismorning/afternoon/evening/week/month/year/centuryorallday/nig

8、ht/week,allthetime,alwaysetc.Note:Pointoutwhattenseortensesareusedinthesentencesandthereasonswhytheyareused.1.WehavestudiedEnglishforaboutfiveyears.Webegantostudyitfiveyearsago.2.Theymovedtothesouthin1990andhavelivedtheresincethen.3.Ericlefthomelasty