说明:引用此文请注明出处,并务请保留后面的有效链接地址,谢谢!<br>三者可表示“当……时候”,区别如下:<br>(1)若主句表示的是一个短暂性动作,从句表示的是一个持续性动作,三者都可用:<br>He fell asleep when [while, as] he was reading.他看书时睡着了。<br>【注】as用于引出一个持续性动词表示“在……期间”时,其谓语通常只能是那些含有动作(action)和发展(development)意味的动词,一般不能是那些不用于进行时态的动词(如be, seem, love, want, agree, see, know, have等),所以下面一句中的while不能换为as:<br>A:I’m going to the post office.我要去邮局。<br>B:While you’re there, can you get me some stamps?当你在邮局时,能帮我买几张邮票吗?<br>(2)若主、从句表示两个同时进行的持续性动作,且强调主句表示的动作延续到从句所指的整个时间,通常要用while:<br>Don’t talk while you’re eating.吃饭时不要说话。<br>I kept silent while he was writing.在他写的时候,我默不作声。<br>但是,若主从句表示的两个同时进行的动作含有“一边…一边”之意思,通常用as:<br>She sang as she went along.她边走边唱。<br>(3)若从句是一个短暂性动作,主句是一个持续性动作,可用as / when但不用while:<br>It was raining hard when [as] we arrived.我们到达时正下着大雨。<br>(4)若主从句表示的是两个同时(或几乎同时)发生的短暂性动作,用as / when:<br>I thought of it just when [as] you opened your mouth.就在你要说的时候,我也想到了。<br>(5)若要表示两个正在发展变化的情况,相当于汉语的“随着”,一般用as:<br>Things are getting better and better as time goes on.随着时间的推移,情况越来越好。<br>
Doing the washing up,Connie was planning her holiday.康妮在洗碗的时刻盘算着怎样度假。The students came into the classroom .学生们又说又笑地走进了教室。As she saw me,she came over. 她看到我时,笑容可掬地走过来。 可表示 行为在主要动作之前或之后。 Antonio remembered sending his mother an email three times last month. 安东尼记得上个月给他母亲发了三次电子邮件.(在前) Mr. Lee went out behind him. 李先生出去后将门随手关上。(在后) 2. v.- -g ing 形式的完成式 v.-ing 形式的完成式由“having + v.-ed 形式”构成,表示动作发生在谓语动词表示的动作之前 ,而时态的表达主要靠谓语动词来加以确定。 I could not recall having heard anyone say that before。我不记得以前听过谁说这样的话。 Having finished his homework,he went to bed. 做完了作业,他去睡觉了。(先“做作业”,后“去睡觉”) He doesn’t remember that.他忘记了曾经答应过我那件事。 She regretted .她很后悔没看这部电影。 I remember you speak on that subject.我记得曾经听见你谈过这个问题。 That weekend,for a while,I went to the library to borrow some new novels. 那个周末,我看了一会儿电视,便去了图书馆借了几本新小说。 ,he has made up his mind to work harder from now on. 他认识到考试失败的原因后,下决心从现在开始要更加努力地学习。 The decision ,the next problem was how to make a good plan. 决定已作出,下一个问题是如何制订一个好计划了。 3. v.- - ing 形式的被动式 -ing形式的一般时的被动式由“being + v.-ed形式”构成,表示主语是v.-ing形式的动作的承受者。