once

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基本解释

• adv.一次；曾经
• conj.一旦
• n.一次
• adj.曾经的

词源解说

• 直接源自古英语的ane，意为一。

同根派生

用法辨析

conj. (连词)

• once用作连词时可引导时间状语从句和条件状语从句。用于前者时意为“一旦…就…”,所引导的从句多很短; 用于后者时意为“只要”,这种条件从句似带有时间条件的含意。
• once引导的从句中有些部分可以省略。

英汉例句

用作副词 (adv.)

• I have been there once.
  我到过那儿一次。

用作连词 (conj.)

• Once you begin, you must continue.
  一旦开了头,你就必须继续下去。

用作名词 (n.)

• Once is enough for me.
  我一次就够了。

词组短语

短语

• once more 再一次;又一次;再次;重新
• once again 再一次;再次见到你;再来一次
• Once Cafe 旺斯咖啡;往咖啡
• once through 单程的;通过;凭借;穿过
• click once 部署;设置;操作;技术

英英字典

剑桥英英字典

• (ONE TIME) one single time
• (PAST) in the past, but not now
• as soon as, or from the moment when

柯林斯英英字典

• If something happens once, it happens one time only.
• Once is also a pronoun.
• You use once with "a" and words like "day," "week," and "month" to indicate that something happens regularly, one time in each day, week, or month.
• If something was once true, it was true at some time in the past, but is no longer true.
• If someone once did something, they did it at some time in the past.
• If something happens once another thing has happened, it happens immediately afterward.
• If something happens all at once, it happens suddenly, often when you are not expecting it to happen.
• If you do something at once, you do it immediately.
• If a number of different things happen at once or all at once, they all happen at the same time.
• For once is used to emphasize that something happens on this particular occasion, that it has never happened before, and may never happen again.
• If something happens once again or once more, it happens again.
• If something happens once and for all, it happens completely or finally.
• If something happens once in a while, it happens sometimes, but not very often.
• If you have done something once or twice, you have done it a few times, but not very often.

专业释义

交通运输工程

• 一次