till和until有什么区别么？

till和until有什么区别么？有人说是until用在否定句中 till用于肯定句 但，until不是也可以用于肯定句么

他们之间的区别在于：
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…

till和until都表示“直到……为止”，主句用延续性动词，主句和从句都用肯定式;表示“直到……才”时，主句用终止性动词，从句用肯定式，主句用否定式。 　　go straight on until you come to the post office and then turn left. 一直向前走到邮局再向左转。 　　she won’t go away till you promise to help her. 在你答应帮助她之前，她不会走的。 　　而他们之间的区别在于： 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…