现在完成时难点瞬间动词转换成延续性动词

现在完成时之瞬间动词转变成延续性动词forsince:for+一段时间，常常可以发现for+数字，forthreemonthsforalongtimeformanyyearsSince+寸间点，常常可以发现a. since+月份，年份，表示时间的几点sinceSeptembersince1990since7oclockb. since一段时间+ago;sincetwoyearsagosincetenmonthsago+last+sincelastmonthsincelastyear现在完成时的结构式hashavedone请注意第三人称：人名.+has当句子为肯定句，且居中出现forsince的时候，句中的时态要用现在完成时，且句中的动词要用延续性动词。当句子为否定句时，句中的动词可以为瞬间动词，表示某个动作不发生的状态已经持续了在有forsince的现在完成时的从句中，如何将瞬间动词转换成延续性动词以borrowkeep为例子Theyborroweditlastweek.Theyhavekeptitsincelastweek.我们已经知道现在完成时的标志就是hashavedone,因此第一步就是看主语，主语时They,我们选择havedone因为borrowkeep.而keep过去分词：kept,因止匕）haveborrowed就需要改成havekept.Since后面只能接时间点，而lastweek就是一个时间点，因此，since后面直接填写lastweek。常考的瞬间动词：过去分词原形动词原形过去式动词过去分词die-be dead died borrow-keep borroweddiediedbedead borrow keepbeen dead borrowed keptleave-beawayfrombuy-have bought begin-be(on) begunbuyhavebegin bebought had began beenjoin-beamemberofbe in become beopenbeinjoinedbecome-bebecomeOpenclose-beopenopenedbeopenfinish-beoverfinishfinishedbeoverputon-wearputputwearcatchacold-haveacoldcaughthavegoto-beingogonebeingettoknow-knowgetknowknownArriveinat-beinarrivearrivedbeinMovecomegetto-beingoout-beoutgobebeenMovecomegetto-beinbeinbeeninjoinjoinedbeeninbecamebeenopenedbeenopenfinishedbeenoverputworncatchcaughthadwentbeeningotgotarrivedbeeninwentgone举例Mr.SmithcametothisschoolinSeptember.Mr.Smith_hasbeenatthisachoolsince_September.分析：1, come-came-come2, 本来应该是填写hascometo，但是cometo要转换成bein3,而be的过去分词为been因此我们填写的内容为hasbeenin4，因为句子中已经有了at，所以我们只需要填写hasbeen