until引导的时间状语从句用什么时态

一、until与by的区别
1.by表示在某特定的时间之前或不迟于某特定的时间,意为"最迟在;不迟于"或"在……之前"等.如:
①I will finish my task by nine.我将在九点钟前完成任务.
②The plane takes off at 10:00,so you must try to be at the airport by 9:30.飞机在十点钟起飞,所以你必须在九点半赶到机场.
2.until用在肯定句,谓语动词通常是延续性动词,如stand,stay,talk,wait等,表示主句动作终止的时间.如:
③I waited until he came back.我一直等到他回来.
④The war lasted until 1945.战争持续到1945年.
如果用在否定句,谓语动词通常是瞬间性动词,如open,start,leave,arrive,finish,stop等,强调主句动作开始的时间.如:
⑤I didn't leave the boy until his mother turned up.直到这孩子的母亲来,我才离开.
⑥The noise of the street didn't stop until it was midnight.街上的噪音直到半夜才停止.
二、until与before的区别
1.可直接换用的情况:在until能使用的句型中,即主句含有否定式终止性谓语动词或肯定式延续性动词,可与before直接替换,意义差别不大.如:
①The students won't go home until / before they finish their homework.学生们要先完成作业才能回家.
②The woman worked in the factory until/before 1990.1990年以前这妇女在这家工厂上班.
2.不可换用的情况:当主句含有肯定式终止性谓语动词时,只能用before不能用until,且before常意为"没来得及……"或"……才……"等.如:
③Einstein almost knocked me down before he saw me.爱因斯坦差不多将我撞倒才看见了我.
④He had measured me before I could get in a word.我还没来得及插话,他就把我的尺寸量好了.
三、not until的倒装与强调结构
1.当Not until位于句首时,句子要倒装.其结构为:Not until+从句/表时间的词+助动词+(主句)主语+谓语+.如:
①Not until the teacher came in did the students stop talking.直到老师进来学生们才停止讲话.
②Not until next week will the sports meet be held.直到下周才开运动会.
2.not until的强调结构为:It is / was not until+从句/表时间的词+that+.上面两句改为强调句为:
③It was not until the teacher came in that the students stopped talking.
④It is not until next week that the sports meet will be held.