复合形式：
|
| all at once adv | (suddenly) | SCSimplified Chinese 忽然 hū rán
TCTraditional Chinese 忽然 |
| | | SCSimplified Chinese 突然 hū rán，tū rán
TCTraditional Chinese 突然 |
| | All at once, I heard a noise in the kitchen. |
| all at once adv | (simultaneously, at the same time) | SCSimplified Chinese 同时 tóng shí
TCTraditional Chinese 同時 |
| | The guests cried "Surprise!" all at once. |
| at once adv | (immediately) | SCSimplified Chinese 立刻，马上，立马 lì kè，mǎ shàng
TCTraditional Chinese 立刻，馬上 |
| | When Beth saw how ill her son was, she called the health centre at once. |
| | 看到儿子病重，贝丝立马给健康中心打了电话。 |
| at once adv | (at one time: simultaneously) | SCSimplified Chinese 同时 tóng shí
TCTraditional Chinese 同時 |
| | I can't clean the house and take care of the children at once. |
| | 我没法同时又看孩子、又打扫房子。 |
| cousin once removed n | (child of your first cousin) | SCSimplified Chinese 表亲子女 |
| cousin once removed n | (first cousin of your parent) | SCSimplified Chinese 隔代表亲 |
| every once in a while expr | (occasionally) | SCSimplified Chinese 每隔一段时间 |
| | | SCSimplified Chinese 偶尔 ǒu ěr
TCTraditional Chinese 偶爾 |
| | | SCSimplified Chinese 有时 yǒu shí
TCTraditional Chinese 有時 |
| | Every once in a while, Paula goes to the gym. |
| for once adv | (for a change, for the first time) | SCSimplified Chinese 就这一次 jiù zhè yí cì
TCTraditional Chinese 就這一次 |
| | | SCSimplified Chinese 仅此一次 jiù zhè yí cì，jǐn cǐ yí cì
TCTraditional Chinese 僅此一次 |
| | | SCSimplified Chinese 只有一次 jiù zhè yí cì，zhǐ yǒu yí cì |
| | Maybe I should do my work a little at a time for once, instead of putting it off. |
| just once adv | informal (one time only) | SCSimplified Chinese 仅此一次 jǐn cǐ yí cì
TCTraditional Chinese 僅此一次 |
| | | SCSimplified Chinese 只有一次 jǐn cǐ yí cì，zhǐ yǒu yí cì |
| | Just once, I wish you would ask politely. |
| | I'll make an exception just once. |
| once a week adv | (on a weekly basis) | SCSimplified Chinese 每周一次 měi zhōu yí cì |
| | Our bins are collected once a week. |
| once again adv | (one more time, as an encore) | SCSimplified Chinese 又一次 yòu yí cì |
| | | SCSimplified Chinese 再一次 yòu yí cì，zài yí cì |
| | Everyone clapped and the band came back to play once again. |
| | 所有人都鼓起掌，然后乐队返台又表演了一次。 |
| once again adv | (yet again) | SCSimplified Chinese 再 zài
TCTraditional Chinese 再 |
| | | SCSimplified Chinese 再次，再一次 zài cì，zài yí cì
TCTraditional Chinese 再次 |
| | | SCSimplified Chinese 再度 zài，zài dù
TCTraditional Chinese 再度 |
| | He has failed the exam once again. |
| | Once again, my son forgot to make his bed. |
| | 再一次，他没能通过考试。 |
| | 我儿子再度忘记整理床铺。 |
| once and again expr | US (repeatedly) | SCSimplified Chinese 一而再 |
| | | SCSimplified Chinese 再三 zài sān
TCTraditional Chinese 再三 |
| once and for all adv | (for the final time) | SCSimplified Chinese 一次了结地 yí cì liǎo jié de |
| | | SCSimplified Chinese 彻底地 yí cì liǎo jié de，chè dǐ de
TCTraditional Chinese 徹底地 |
| | You said yes, then you said no. Tell me once and for all, will you marry me? |
| once before adv | (on one previous occasion) | SCSimplified Chinese 曾经，有一次 céng jīng，yǒu yí cì
TCTraditional Chinese 曾經 |
| once in a blue moon adv | figurative (very rarely) | SCSimplified Chinese 千载难逢地 |
| | | SCSimplified Chinese 极为罕见地 |
| | He only calls once in a blue moon. |
| once in a lifetime adv | (extremely rarely) (机遇等) | SCSimplified Chinese 一生一次，千载难逢
TCTraditional Chinese 千載難逢 |
| | A chance like this only comes along once in a lifetime. |
| once in a while adv | (occasionally) | SCSimplified Chinese 偶尔 ǒu ěr
TCTraditional Chinese 偶爾 |
| | | SCSimplified Chinese 时而 ǒu ěr，shí ér
TCTraditional Chinese 時而 |
| | | SCSimplified Chinese 有时 ǒu ěr，yǒu shí
TCTraditional Chinese 有時 |
| | I hear from old school friends once in a while. |
| | 我有时还能收到老同学的来信。 |
| once more adv | (yet again) | SCSimplified Chinese 再 zài
TCTraditional Chinese 再 |
| | | SCSimplified Chinese 又 zài，yòu
TCTraditional Chinese 又 |
| | Once more you have failed to get your essay in on time. |
| once more adv | (one more time) | SCSimplified Chinese 再一次 zài yí cì |
| | | SCSimplified Chinese 又一次 zài yí cì，yòu yí cì |
| | Can you please show me once more how it works? |
| once or twice expr | (a couple of times, a few times) | SCSimplified Chinese 几次 jǐ cì |
| | | SCSimplified Chinese 一两次 |
| once removed adj | (relative: one generation older) (年长一辈的亲戚) | SCSimplified Chinese 远房的，隔代的 yuǎn fáng de |
| | My father's first cousin is my first cousin once removed. |
| once removed adj | (relative: one generation younger) (年轻一辈的亲戚) | SCSimplified Chinese 远房的，隔代的 yuǎn fáng de |
| | My first cousin's daughter is my first cousin once removed. |
| once upon a time adv | (start of a fairy tale) | SCSimplified Chinese 很久以前 hěn jiǔ yǐ qián |
| | Once upon a time, in a land far away, there lived an orphan girl with her wicked stepmother. |
| | 很久以前，在一片遥远的国度，住着一位没有爸爸妈妈的女孩和她邪恶的继母。 |
| once-in-a-lifetime adj | (opportunity: very rare) (机遇等) | SCSimplified Chinese 一生一次的，千载难逢的 |
| | The brothers thought the trip around the world was a once-in-a-lifetime opportunity. |
give [sb/sth] the once-over,
give [sb/sth] a once-over v expr | informal (inspect quickly) (非正式用语) | SCSimplified Chinese 草草打量，粗略查看 |
| | When I submitted my report to the CEO, he gave it the once-over and then gave me a thumbs up. |
give [sth] the once-over,
give [sth] a once-over v expr | informal (clean [sth] quickly) (非正式用语) | SCSimplified Chinese 迅速清洁
TCTraditional Chinese 迅速清潔 |
| | | SCSimplified Chinese 迅速打扫 |
| | I had just finished giving the living room a once-over when the guests arrived. |
| only once adv | (on one occasion only) | SCSimplified Chinese 只有一次 zhǐ yǒu yí cì |
| | I've been to Paris only once but would like to return some day. |
| only once adv | (a single time without repetition) | SCSimplified Chinese 只一次 zhǐ yí cì |
| | | SCSimplified Chinese 仅一次 zhǐ yí cì，jǐn yí cì |
| | Press the "enter key" only once. |
there was once,
there once lived expr | (start of a fairy tale) (童话故事开头) | SCSimplified Chinese 曾经 céng jīng
TCTraditional Chinese 曾經 |
| | | SCSimplified Chinese 从前 céng jīng，cóng qián
TCTraditional Chinese 從前 |
| | There was once a princess with very long hair. |
| too much at once n | (sudden excess of [sth]) | SCSimplified Chinese 突然过量 tū rán guò liàng
TCTraditional Chinese 突然過量 |
| | I took a big gulp of beer and got too much at once. |