时态中典型用法.ppt

时态中的典型用法;1．在if, unless, even if 引导的条件状语从句中，在when, before, until (till), as soon as, the moment, once 引导的时间状语从句中，在no matter what /who / which / when / where / how 或whatever, whoever, whichever, whenever, wherever, however 引导的让步状语从句中，如果主句是将来时（往往出现will / shall / can / must ）或主句是祈使句，从句用一般现在时表示一般将来时。 ;① I’ll go with you as soon as I finish my work. ② Hundreds of jobs will be lost if the factory closes. ③ — Can I join your club, Dad ? — You can when you get a bit older. ④ If city noises are not kept from increasing, people will have to shout to be heard even at the dinner table 20 years from now. ;2．would 与used to ;① would 与used to 都可用来表示过去经常性或习惯性的动作，常常可以换用。如： When we were boys we used to / would go swimming every summer. 小时候，每天夏天我们都要去游泳。 He used to . would spend every penny he earned on books. 过去他通常把挣来的钱全花在买书了。;② would 之后要接表示动作的动词，不接表示状态的动词，而used to 则无此限制。如： He used to be nervous in the exam. ③ would 表示反复发生的动作。如果某一动作没有反复性，就不能用would, 只能用used to。如： And from that day on, as soon as the table was cleared and the dishes were gone, Mother would disappear into he sewing room to practice. 从那天起，只要碗盘撤掉、饭桌清理干净，妈妈就马上躲进做针线活的房间练习起来。（具有反复性） I used to live in Beijing. 我过去住在北京。（没有反复性） ;④ used to 表示过去经常性或习惯性的动作或状态，现在已经结束（含有较强的“今非昔比”的意思），would 则只表示说话者对过去一种回想心情，有可能再发生。如： People used to believe that the earth was flat. 过去，人们总以为地球是扁平的。（现在已不再这样认为） He would go to the park as soon as he was free. 过去他一有空就去公园。（现在有可能再去）;3．be +动词不定式;① 表示按计划或安排要做的事。例如： When are you to leave for two days to New York ? 你什么时候去纽约？ She is to get married next month. 她下个月结婚。 这种结构也可用于过去。was / were to do sth. 表示曾经计划要做某事，但不表明计划是否被执行，或表示“命运（即使中注定要发生的事）”，而非计划；was / were to have done sth. 表示未曾实现的计划 ;I felt excited because I was soon to leave home for the first time. 我感到很激动，因为我很快就要首次离开家了。 We were to have told you, but you were not in. 我们本来想告诉你的，但是你不在家。;② 表示“指令”，相当于should, ought to, must, have to。例如： You are to report to the police. 你应该报警。 What is to be done ? 应该怎么办呢？ This medicine is to be taken three times a day. 这种药一天要服