请问英语高手：I didn't go to bed until finishing my homework.这句话有没有语法错误？
=I did not go to bed until I finished my homework （如果主语主语和从句主语不是同一个主语，不可以用UNTIL DOING 这个结构，以定要把从句主语和谓语写上去.
(until 做连词，后接句子，做介词，后接名词和名词短语，以及动名词）
解答如下：
以上是考察一个 not until 用 起结构为
基本结构：NOT +主句+UNTIL +从句 (备注NOT 是否定主句谓语动词）
例如：We did not get off the bus until it stopped completely
主语+助动词否定式+do Something A until 主语+谓语DO SOMETHING B
意识，只有UNTIL 后面B 动作发生了，A 动词方可以发生
Sb +doesn't ;didn't do sth A until doing sth B
Sb doesn't /didn/t do sth A until Sb does sth B
SOMEBODY +AUXILIARY VERB NEGATIVE FORM +DO SOMETHING A UNTIL DOING SOMETHING B
Somebody +Auxiliary Verb Negative Form +Does Something A +Until Sombody does Something B
I did not realize she was Li Yuchun until she took off her glasses
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。
No. Not until this note from his best friend, another teacher, informed me of his passing.
不——直到他最要好的朋友，另一位老师，来信告之他去世的消息时，我一直不知道。
We'll never find Truth in her entirety, at least not until the Second Coming, and who knows when that will be?
我们永远找不到完整的真理，至少在第二次到来之前不能，谁知道那将是什么时候呢？
1、He is absent till/until now. 他到现在还没来
2、He didn't show up till/untill now. 他到现在才来
详解
till / until在表达方式和意义上的特殊性：until是till的强调形式，但是它们表达的意义是相同的，都表示"直到某时"。不过，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 .
此两个连词意义相同。肯定形式表示的意思是"做某事直至某时"，动词必须是延续性的。否定形式表达的意思是"直至某时才做某事"。动词为延续性或非延续性都可 以。 正确使用这两个连词的关键之一就在于判断句中的动词该用肯定式还是否定式。
肯定句：
I slept until midnight. 我一直睡到半夜时醒了。
Wait till I call you. 等着我叫你。
（在肯定句中可用before代替 Let's get in the wheat before the sun sets.）
否定句：
She didn't arrive until 6 o'clock.
她直到6点才到。
Don't get off the bus until it has stopped.
公共汽车停稳后再下车。
I didn't manage to do it until you had explained how. 直到你教我后，我才会做。
1)Until可用于句首，而till通常不用于句首。
Until you told me, I had heard nothing of what happened.
直到你告诉我以前，出了什么事我一点也不知道。
2)Until when 疑问句中，until要放在句首。
---Until when are you staying? 你呆到什么时候？
--- Until next Monday. 呆到下周一。
注意：否定句可用另外两种句式表示。
(1）Not until …在句首，主句用倒装。
Not until the early years of the 19th century did man know what heat is.
直到19 世纪初，人类才知道热能是什么。
Not until I began to work did I realize how much time I had wasted.
直到我开始工作，我才认识到了我已蹉跎了几多岁月。
(2) It is not until… that…
有两个很明显的错误。
如果，此处的虚拟是对将来的虚拟
那么，句子应该为 ; I would not to bed until I have finishied my homework
2.如果，此处的虚拟是对过去将来时的虚拟
那么，句子应该为 ; I would had not to bed until I had finishied my homework
not until 的结构是连接前后两个句子。
如果你对我的回答还算满意的话，别忘了采纳哦，亲。