once/wʌns/

adv

1. 一次，仅一次

• She goes to the supermarket once a week. 她每周去一次超市。

2. 曾经，一度

• The old man was once famous, but now nobody knows him. 这位老人曾经很有名，可现在没人知道他了。

• I've met him once or twice before. 我见过他一两次。

词组all at once

1. 突然

• All at once she lost her temper. 她突然大发雷霆。

2. 同时，一起

• Don't talk all at once. One at a time, please. 大家不要同时发言，一个一个轮流讲。

at once

1. 立刻，马上

• She told him to leave the room at once. 她要他立即离开房间。

2. 同时

• I can't do two things at once. 我不能同时做两件事请。

once again(或more) 再一次

• It once again proves that no one can stem the tide of history. 这再一次地证明，历史的潮流是谁也阻挡不住的。

once and again 一而再，好几次

• Why did she do that experiment once and again? 为什么她再三地做那个试验？

once (and) for all 一劳永逸地；最终地；彻底地

• I am going to settle this matter once for all. 我要彻底地解决这个问题。

Once bit(或bitten), twice shy 见bite once in a blue moon 非常稀罕 once in a while 偶尔

• Once in a while, he goes with us to the movies on Saturday night. 他偶尔在星期六的晚上同我们一道去看电影。

once too often (曾经多次逃脱)这次却未能幸免

• He exceeded the speed limit once too often and was fined $10. 他因超速次数太多而被罚款10美元。

once upon a time 见time¹