[狀語從句]比較until和till

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此兩個連詞意義相同??隙ㄐ问奖硎镜囊馑际?做某事直至某時",動詞必須是延續(xù)性的。否定形式表達(dá)的意思是"直至某時才做某事".動詞為延續(xù)性或非延續(xù)性都可以。正確使用這兩個連詞的關(guān)鍵之一就在于判斷句中的動詞該用肯定式還是否定式??隙ň洌篒 slept until midnight. 我一直睡到半夜時醒了。
    Wait till I call you. 等著我叫你。(在肯定句中可用before代替。例如 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,我才會做。
    區(qū)別:1)until可用于句首,而till通常不用于句首。例如:
    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。例如:
    ——Until when are you staying? 你呆到什么時候?
    —— 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。例如:
    Not until the early years of the 19th century did man know what heat is. 直到19 世紀(jì)初,人類才知道熱為何物。
    Not until I began to work did I realize how much time I had wasted. 直到工作,才認(rèn)識到我已蹉跎了幾多歲月。
    2)It is not until… that… .例如:
    It was not until I began to work that I realized how much time I had wasted.