保持句意不变

关于not until

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。例如：
He didn't go to sleep until 12 last night .
他昨晚直到十二点钟才睡觉。
They didn't realize their fault till we pointed it out to them .
直到我们向他们指出了他们的错误，他们才意识到。
Not until we pointed out their fault to them did they realize it .
直到我们向他们指出了他们的错误，他们才意识到。
但是，当主句是肯定句时，它引出的意思是"直到（某时某动作停止了）" 。例如：
The students made much noise till the teacher came into the classroom .
直到老师走进教室学生们才停止了大声喧哗。
The young couple were very happy until they used up all their money .
那对年青夫妇直到花光了所有的钱才沮丧起来。
另外，until 可以放在句首而till则不行。我们可以说：Until they used up all their money, the young couple were very happy .我们却不可以说：Till they used up all their money, the young couple were very happy .

有关hardly when /
scarcely when/
no sooner than

如下

hardly when

Hardly had the thief seen the policeman when he ran away.
= Scarcely had the thief seen the policeman before he ran away.
=No sooner had the thief seen the policeman than he ran away.

综上 原题是填空题 结构上不倒装 用He didn't go to bed until his mother came back.

He didn't go to bed until his mother came back.
是一样的，我前一段时间学过，相信我，没错的
o(∩_∩)o...
真的是这个，
如果你不信的话，那我们也没有办法了……

He didn't go to bed until his mother came back.

He didn't go to bed until his mother came back.
not .....until 直到。。。才。。。

He _had_ go to bed _before__ his mother came back
他已经休息拉，在他母亲回来之前。