Not untill 11th century,when a young lady brought a fork to

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.
另外,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…

Untill表示 直到
not untill 表示 到 （什么时候） 才 （怎么怎么样）
例句
You must keep reading untill 7:00
你必须读书到7点
I did not reach home untill 11:00
我直到11点才回家
两者不是一个意思
untill只是表明一个条件（意思是 直到＋一个条件）
not untill表示直到（一个条件）后 才发生什么动作 是跟动作有关系的

He didn~t realize the importance of health until he was ill.
Not until he was ill did he realize the importance of health.
It was not until he was ill that he realized the importance of health.

not ...until 引导时间状语从句,从句不能用将来时,主句是一般将来时,从句用现在时.
Don't get off the bus until it stops.(主句是祈使句从句用现在时）
He didn't go to bed until his mother came back.（主句是过去时,从句时态一致）
He won't call you until he finishes his work.(主句用一般将来时,从句用现在时

Not…until…句型尽管在某些情况下可与before互换使用,但在强调句中一般仍用until;
1).It was not until he told me that I knew it.直到他告诉我我才知道这件事.
2）.It was not until he finished his homework that he went home.直到完成作业他才回家.
3）放于句首时用until.
For example:
Antil he finished his homework ,he didn’t go home.直到完成作业他才回家.
应注意：在使用not until时,若not until放于句首,句子应部分倒装.For example:
Not until he finished his homework,did he go home.直到完成作业他才回家
琦姐用我的

不,可以分开用
not...until是直到...才
until是直到
e.g.他一直等到火车开动.
He waited until the train (stanted).=left
直到雨停他们才出发.
They didn't leave until the rain stopped.

第一种正确.
not...until...的倒装句型中,until引导的时间状语从句无须倒装,只需把含有not的主句变成肯定句后再倒装即可.
所以是：Not until he went to middle school did he start studying English.
当然,如果not...until...中的until只引导时间状语而不是时间状语从句就更容易了：时间状语照抄,句子倒装即可.
如：Not until middle school did he start studying English.

Not…until…句型尽管在某些情况下可与before互换使用,但在强调句中一般仍用until; 1).It was not until he told me that I knew it.直到他告诉我我才知道这件事.2）.It was not until he finished his homework that he went home.直到完成作业他才回家.3）放于句首时用until.For example:Antil he finished his homework ,he didn’t go home.直到完成作业他才回家.应注意：在使用not until时,若not until放于句首,句子应部分倒装.For example:Not until he finished his homework,did he go home.直到完成作业他才回家 琦姐用我的

not untill