同学你好，该知识点来自沪江网校《2019年6月CET英语六级【全程班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好

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: Not until the teacher came in did the students stop talking.直到老师进来学生们才停止讲话。
2. not until的强调结构为:It is / was not until+从句/表时间的词+that+...。上面句改为强调句为: It was not until the teacher came in that the students stopped talking.  因此呢,现在的用法属于not until 的强调结构。这种用法很常见哦!