not until的用法及例句
not...until的基本含义是直到...才，在...以前不。not...until的三种用法有：基本结构、强调句结构、倒装句结构。
not...until的基本结构
基本结构：not主句+until+从句
例句：
We did not get off the busuntil it stopped.
直到车停了，我们才下了公交车
not...until的强调句结构
强调句结构：It is / was not until+从句/表时间的词+that+主句
1、not until 后边一般是时间点，如：
It was not until midnight that it stopped raining. 直到半夜雨才停下来。
It was not until five o'clock in the afternoon that they finished their work. 直到下午五点他们才完成工作。
2、not until 后边也可以是陈述的句子，如：
It was not until he came to China that he realized the great change in recent decades. 直到他来到中国，他才意识到最近几十年的巨大变化。
It was not until he got sick seriously that he realized the value of a healthy body. 直到他生重病，他才意识到一个健康体魄的价值。
3、not until 后边还可跟介词短语，如：
It was not until after Friday that I got his reply. 直到星期五之后，我才得到他的答复。
我们可以注意到，在以上列举的例句中，“It is/was not until .... that 从句”句式中的“that 从句”部分都是采用一般的陈述语序(类似于宾语从句)。时态上一般采用过去时，与 it was 相呼应。
not...until的倒装句结构
倒装句结构：Not until+从句+倒转的主句（主倒从不倒）
not until 引起的时间状语置于句首时，句子的主谓应部分倒装。由 not until 引导的时间状语从句位于句首时，主句应部分倒装，从句语序不变。
例句：
Not until 1998 did he return to his hometown.
直到 1998 年他才回到家乡.
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.
