此兩個(gè)連詞意義相同�？隙ㄐ问奖硎镜囊馑际�"做某事直至某時(shí)"，動(dòng)詞必須是延續(xù)性的。否定形式表達(dá)的意思是"直至某時(shí)才做某事"。動(dòng)詞為延續(xù)性或非延續(xù)性都可　以。 正確使用這兩個(gè)連詞的關(guān)鍵之一就在于判斷句中的動(dòng)詞該用肯定式還是否定式。
　
　 肯定句：
　 i slept until midnight. 我一直睡到半夜時(shí)醒了。
　 wait till i call you.　 等著我叫你。
　 （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點(diǎn)才到。
　 don't get off the bus until it has stopped.
　 公共汽車停穩(wěn)后再下車。
　 i didn't manage to do it until you had explained how.　 直到你教我后，我才會(huì)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.
　　直到你告訴我以前，出了什么事我一點(diǎn)也不知道�！�
2)until when 疑問句中，until要放在句首。
　 ---until when are you staying?　你呆到什么時(shí)候？
　 --- until next monday.　呆到下周一。　

注意：否定句可用另外兩種句式表示。
(1）not until …在句首，主句用倒裝。
　　not until the early years of the 19th century did man know what heat is.
　　直到19 世紀(jì)初，人類才知道熱能是什么。
　　not until i began to work did i realize how much time i had wasted.
　 直到我開始工作，我才認(rèn)識(shí)到了我已蹉跎了幾多歲月。
(2)　it is not until… that…