l基本含义是“直到...才”。
I did not go home until my mother called me.
我直到我妈妈打电话给我才回家。
Not until Father came back did we begin to have supper last night.
昨晚直到父亲回来，我们才开始吃晚饭。
not until的倒装与强调结构，not until通常与非延续性动词连用，强调主句所表示的状态或情景从until所表示的'时间才发生，主句必须是否定句。
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
（1）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 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
（1）It was not until the teacher came in that the students stopped talking.
（2）It is not until next week that the sports meet will be held.
