1.till与until在用法的区别 :
till和until都可以作为介词和连词，用在肯定句中时，二者均可表示“直到……为止”，
相当于before 。
例如： I will wait till（until）seven o‘clock．
我会一直等到7点钟。（介词）
She lived in Tokyo till（until）she died．
她在东京一直住到去世。（连词）
till与until用在否定句中，均可表示“在……以前”或“直到……才”。
例如： Tom didn‘t come back till（until）midnight．
汤姆到半夜才回来。（介词）
The boys won‘t come home till（until）it is dark．
男孩子们不到天黑不回家。（连词）
需要注意的是：till多用于普通文体，而 until则用于多种文体，并且在句子开头时，用 until而不用till。
例如： 在他回来之前，什么也不能做。
译：Until he comes back，nothing can be done．（√）
Till he comes back，nothing can be done．（×）
not…until/till… 意为“直到……才……”，表示until/till 所表示的时间一到，主句谓语动词所表示的动作才发生。
He didn’t go to bed until/till his mother came back.
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。
I did not go home until my mother called me.
我直到我妈妈打电话给我才回家.
It was not until 1911 that the first of the vitamins was identified.
直到1911年才发现了第一种维生素。
2、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:
We didn’t begin to have supper last night until our father came back.
Not until our father came back did we begin to have supper last night.
She didn’t have a rest until she finished the work.
Not until she finished the work did she have a rest.
直到完成工作他才休息。
The shudents didn’t stop talking until the teacher came in.
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。
The sports meet will not be held until next week.
Not until next week will the sports meet be held.直到下周才开运动会。
注意，not until引导的时间状语从句放句首，主句采用部分倒装，从句语序不变。
3、not until的强调结构为:It is / was not until 从句/表时间的词 that .. 例句：
I didn’t realize she was a film star until she took off her glasses.
It was not until she took off her glasses that I realized she was a film shar.
直到她摘下墨镜，我才意识到她是一个电影明星。
It is not until next week that the sports meet will be held. 直到我结婚的时候，我才有钱买了自己的房子。
.She didn't remember her appointment with the doctor until yesterday.
It was not until yesterday that she remembered her appointment with the doctor. Not until yesterday did she remember her appointment with the doctor.
她直到昨天才想起和医生的约会。
The shudents didn’t stop talking until the teacher came in.
It was not until the teacher came in that the students stopped talking.
直到老师进来学生们才停止讲话。
The sports meet will not be held until next week.
It is not until next week that the sports meet will be held.
直到下周才开运动会。
