if引导的虚拟语气条件句

if引导的虚拟语气条件句曲线正矢设置讲义1曲线正矢设置讲义1曲线正矢设置讲义1曲线正矢设置讲义曲线正矢设置讲义讲解关于曲线的基础知识，主要有以下三方面的内容：1.曲线绳正法、2.曲线正矢设置。绳正法：利用曲线正矢与曲线之间关系，改正正矢，使其恢复原来曲率，通过相应拨量，拨正到原来位置。一、曲线整正的基本原理（一）两条假定1．假定曲线两端切线方向不变，即曲线始终点拨量为零。2．曲线上某一点拨道时，其相邻测点在长度上并不随之移动。（二）四条基本原理1．现场正矢的合计等于正矢的合计。2．曲线上任意点的拨动，对相邻点正矢的影响量为拨动点拨动量的二分之一，其方向相反。3．曲线上各点正矢之和为一常数。4．曲线上各点正矢差之代数和为零，即曲线终点的拨量等于零。（三）绳正法拨正曲线基本要求1.曲线两端直线轨向不良，一般应事先拨正，两曲线间直线段较短时，可与两曲线同时计算拨正；2.在外股钢轨上用钢尺丈量，每10m设置一个测点（曲线头围是否在测点上不限）；3.在风力较小条件下，拉绳测量每个测点正矢，测量三次取平均值；4.按绳正法计算拨道量，计算时不宜为减少拨道量而大量调整计划正矢；5.设置拨道桩，按桩拨道。二、曲线正矢容许偏差三、圆曲线计划正矢计算（一）圆曲线半径、弦长、正矢之间的关系（二）头尾标桩齐全的曲线计划正矢计算1.圆曲线上中间各点计划正矢（1）圆曲线计划正矢的计算fc=50000/Rfc=现场实量正矢合计/圆曲线分段数（2）测点正好在圆曲线始终点时的计划正矢计算圆曲线始终点正矢f始（终）=fc/2（3）测点在圆曲线始终点附近时的计划正矢计算圆曲线始终点附近测点的计划正矢=fc×该点纵距率2.缓和曲线正矢（1）圆曲线计划正矢计算（2）测点正好在缓和曲线始终点时的计划正矢计算f始=fN/6f终=fc-f始fi=NifN（3）测点在缓和曲线始终点附近时的计划正矢计算①缓和曲线始终点附近测点计划正矢缓和曲线始点附近测点（2、3）正矢=fN×（2、3）测点的纵距率缓和曲线终点附近测点（5、6）正矢=fC-fN×（5、6）测点的纵距率②缓和曲线中间各测点计划正矢缓和曲线中间各测点正矢=fN×自缓和曲线始点到所求点的分段数有关曲线正矢设置简单概况，就与各位共同学习到这，在讲解过程中存在的不足和缺陷，还请各位多提出宝贵的意见。谢谢各位！虚拟语气LearningGoals：1.Knowingwhatthesubjunctivemoodrefersto.2.Knowingthedifferenceformsofthesubjunctiveforms.3.Masterthestructureofthesubjunctivemoodabout“if”.4.Practices.虚拟语气概念：1.表示说话人所说的话不是一个事实，而是一个假设、怀疑、猜测等（常见于条件状语从句或让步状语从句）。2.表示说话人的愿望、建议、要求、命令等（常见于名次性从句）。简单来说：不是事实或不大可能发生的事情，用虚拟语气来表述。If引导的虚拟条件句注意：要区分if引导的真实条件句和if引导的虚拟条件句表示虚拟的，几乎无法实现的时候，采用虚拟语气。If引导的虚拟条件句TYPES:特殊：错综时间/倒装句省略IF等一.与过去事实相反Ifhehadgotupearlier,hecouldhavecaughtthetrain.If引导的虚拟条件句主句与过去事实相反的假设If+主语+had+动词的过去分词（即：If+动词过去完成时）主语+would(should/might/could)+havedone二.与现在事实相反IfIwereyou,Iwouldbuyaredskirt.IfIhadamilliondollars,Iwoulddonate30%ofittothecharity.If引导的虚拟条件句主句与现在事实相反的假设If+主语+动词过去式（be动词一般用were）即：If+一般过去时If+主语+would(could/should/might)+动词原形三.与将来事实可能相反Ifitrainedtomorrow,Iwouldn’tattendtheparty.Ifitweretoraintomorrow,Iwouldn’tattendtheparty.Ifyoushouldcometomorrow,youwouldfindthenewmanagerworkingintheoffice.If虚拟条件句主句与将来事实可能相反的假设1.If+主语+动词过去式If+主语+wereto+动词原形3.If+主语+should+动词原形主语+would(could/should/might)+动词原形特例1.错综时间条件句定义：主句和从句动作发生的时间不同例1）Iftheyhadstudiedhard,theycouldfinishtheworkinaveryshorttime.如果他们当时刻苦学习，现在就能快速完成这份工作了（从句说明过去，主句说明现在）。2）IfIwereyou,Iwouldhavegonetoherbirthdaypartyyesterday.如果我是你，我就去参加她昨天的生日聚会了（从句说明现在，主句说明过去）。♦要根据动作发生的时间选择恰当的动词形式。与过去相反，以前没有刻苦学习与现在事实相反，现在没有快速完成特例2.省略If的条件从句如果条件句中有were/had（助动词）/should时，可使用倒装句结构——省略If，把were/had（助动词）/should放句首。如果条件句是否定句时，not应置于主语后，不能与were/had（助动词）/should等缩略成weren’t/hadn’t/shouldn’t.例：HadIseenhimthen,Iwouldhavebeenveryhappy.=IfIhadseenhimthen,Iwouldhavebeenveryhappy.ShouldIhavetime,Iwouldgowithyou.=IfIshouldhavetime,Iwouldgowithyou.WereInotsobusy,Iwouldgototheconcert.=IfIweren’tsobusy,Iwouldgototheconcert.Practice1.Ifyouhadtoldmeinadvance,I____himattheairport.A.wouldmeetB.wouldhavemetC.wouldhadmetD.shouldmeetPractice1.Ifyouhadtoldmeinadvance,I____himattheairport.A.wouldmeetB.wouldhavemetC.wouldhadmetD.shouldmeet2.Ifit___tomorrow,Iwouldnotattendtheparty.A.rainedB.rainsC.hadrainedD.weretorain3.IwouldhavegonetothemeetingifI__time.A.hadhadB.havehadC.hadD.wouldhavehadIfit___tomorrow,Iwouldnotattendtheparty.A.rainedB.rainsC.hadrainedD.weretorain3.IwouldhavegonetothemeetingifI__time.A.hadhadB.havehadC.hadD.wouldhavehadIfit___tomorrow,Iwouldnotattendtheparty.A.rainedB.rainsC.hadrainedD.weretorain3.IwouldhavegonetothemeetingifI__time.A.hadhadB.havehadC.hadD.wouldhavehad4.Ifmefather___herenow,he___tellmewhattodo.A.were;wouldB.was;illC.hadbeen;wouldD.is;ill5.Ifhe___myadvice,hewouldn’thavelosthisjob.A.followedB.shouldfollowC.hadfollowedD.wouldfollow4.Ifmefather___herenow,he___tellmewhattodo.A.were;wouldB.was;illC.hadbeen;wouldD.is;ill5.Ifhe___myadvice,hewouldn’thavelosthisjob.A.followedB.shouldfollowC.hadfollowedD.wouldfollow4.Ifmefather___herenow,he___tellmewhattodo.A.were;wouldB.was;illC.hadbeen;wouldD.is;ill5.Ifhe___myadvice,hewouldn’thavelosthisjob.A.followedB.shouldfollowC.hadfollowedD.wouldfollow6.IfI__inthe22ndcentury,I__myvocationinaverydifferentway.A.shouldlive;wouldspendB.willlive;shouldspendC.areliving;shouldhavespentD.willbeliving;wouldhavespent7.__itraintomorrow,wewouldhavetoputoffthevisittoMountainTai.A.WereB.ShouldC.WouldD.Will6.IfI__inthe22ndcentury,I__myvocationinaverydifferentway.A.shouldlive;wouldspendB.willlive;shouldspendC.areliving;shouldhavespentD.willbeliving;wouldhavespent7.__itraintomorrow,wewouldhavetoputoffthevisittoMountainTai.A.WereB.ShouldC.WouldD.Will6.IfI__inthe22ndcentury,I__myvocationinaverydifferentway.A.shouldlive;wouldspendB.willlive;shouldspendC.areliving;shouldhavespentD.willbeliving;wouldhavespent7.__itraintomorrow,wewouldhavetoputoffthevisittoMountainTai.A.WereB.ShouldC.WouldD.WillTHANKYOU! 结束语谢谢大家聆听！！！