当主句是否定句时,它引出的意思是"直到（某时）（某动作）才（发生）" ,这时候常会出现"not until …"的结构,如果将 "not until …"的结构放在句首,那么主句要写成倒装句.
其结构为:Not until+从句/表时间的词+助动词+(主句)主语+谓语+.
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.
until的强调结构为:It is / was not until+从句/表时间的词+that+:
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.
