油管aiden:请介绍下until的用法。

Until直到….为止, not until直到…才

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。

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。

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…这是一个强调结构。如本题。

Till的用法基本相同，但

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。

还可以参考http://www.caiabc.com/word/ShowArticle.asp?ArticleID=728
讲解很详细的

until
来自中古英语untill<un- + till到
[Qn5tIl]
prep, conj
直到…为止
We can't go until Thursday.
我们要到星期四才能去。
I couldn't sew until I was six.
我直到六岁时才会用针缝东西。
We can't start the job until we have the approval from the authority concerned.
没有有关当局的批准我们不能开始这项工作。
He waited until the volcano became quiet and he was able to return two days later.
他一直等到火山平息下来,两天后他才得以重回火山上。
（亦作： till）

until
[En5til, Qn5til]
prep.
(=to the time of)直到...时, 到...为止
[常用在否定句中](=before)在...以前; 直到...才; 不到...(不)
until his death
直到他死
until four o'clock
直到四点钟
He did not go until night.
他直到夜里才走。
It was not until yesterday that I noticed it.
直到昨天我才注意到这件事。

until
conj.
(=up to the time when)到...时为止; 直到...时
[用在否定句中](=before)在...以前; 不到...(不)
直到...地方; 直到...程度
I will wait here until the concert is over.
我将一直在这儿等到音乐会结束。
U-he returns, nothing can be done.
他不回来什么也不能做。
Go straight on until you come to a large building.
一直往前走, 直到你走到一座大楼。
【说明】till与until同义, 但在主句前的从句或短语中, 通常用until。例如: U-then, I knew nothing at all about it. 在那时以前, 我对这事一无所知。

unless and until=until

until
AHD:[緉-t筶挥
D.J.:[(n6til]
K.K.:[(n6t!l]
prep.
Up to the time of:
We danced until dawn.
Before (a specified time):
She can't leave until Friday.
Scots
Unto; to.
until
conj.
Up to the time that:
We walked until it got dark.
Before:
You cannot leave until your work is finished.
To the point or extent that:
I talked until I was hoarse.
See: till2

Middle English
un-[ up to ]
fromOld Norse und
*See Also : ant- In Appendix
til[ till ]
*See Also : till2

until
AHD:[緉-t筶挥
D.J.:[(n6til]
K.K.:[(n6t!l]
prep.
Up to the time of:
直到…的时候：
We danced until dawn.
我们跳舞一直跳到天亮
Before (a specified time):
在（某一特定的时间）以前：
She can't leave until Friday.
在星期五之前她不能离开
Scots
【苏格兰】
Unto; to.
去到…的上面；去…
until
conj.
Up to the time that:
直到…的时候：
We walked until it got dark.
我们一直走到天黑了下来
Before:
在…之前：
You cannot leave until your work is finished.
在你的工作被完成以前你不能离开
To the point or extent that:
直到直到…的程度：
I talked until I was hoarse.
我一直说到声音嘶哑
See: till2

Middle English
中古英语
un-[ up to ]
un-[ 直到 ]
fromOld Norse und
源自古斯堪的纳维亚语 und
*See Also : ant- In Appendix
til[ till ]
til[ 直到；直至 ]
*See Also : till2

①till与until的意义和用法相同,但句首一般不用till而用until。②两者皆可用作介词和连词,但两者都不能没有宾语,因此都不是副词。③要注意在使用until或till表示汉语“直到...才”的时候,常常要把汉语的肯定句改为否定句。
Till和until普遍认为在口语和书面语中都可通用，而作为句子的第一个词时，until更为常用：
Untilyougetthatpaperwrittendon'teventhinkaboutgoingtothemovies.·Tillisactuallytheolderword,withuntilhavingbeenformedbytheadditiontoitoftheprefixun-,meaning“upto.”Inthe18thcenturythespelling'tillbecamefashionable,asiftillwereashortenedformofuntil.Although'tillisnownonstandard,'tilissometimesusedinthiswayandisconsideredacceptable,thoughitisetymologicallyincorrect.
除非你把那篇文章写完了，否则别想去看电影。Till实际上是这两个词中较早使用的一个，在它前面加一个表示“直到”的前缀un-构成了until。在18世纪，'till这种拼写方式很时髦，似乎till成了until的缩写形式。尽管'till现在不是标准的用法，即使从词源学角度讲它是不正确的，'til有时还这样使用，而且被认为是可以接受的

until
[Qn5tIl]
prep., conj.
直到…为止
We can't go until Thursday.
我们要到星期四才能去。
I couldn't sew until I was six.
我直到六岁时才会用针缝东西。
We can't start the job until we have the approval from the authority concerned.
没有有关当局的批准我们不能开始这项工作。
He waited until the volcano became quiet and he was able to return two days later.
他一直等到火山平息下来,两天后他才得以重回火山上。