“Once” in Chinese 2 – yídàn

Posted on by tiffany

OneDotDot Chinese
Grammar · HSK 5
Grammar Point · HSK 5

一旦 yídàn — “Once”

The structure 一旦 yídàn⋯就 jiù⋯ is often used in Chinese to express “once.” In this pattern, 就 jiù serves as a condition marker and can be translated as “then” or “in that case.” This structure indicates that once a certain condition is met, the action or consequence in the second part will occur. It’s a formal structure in Chinese.

Once 一旦 yídàn 就 jiù Chinese grammar

Once a condition introduced by 一旦 yídàn is met, the consequence marked by 就 jiù follows automatically.

1 Structure

一旦 yídàn + Condition + 就 jiù + Consequence

The subject can come either before or after 一旦 yídàn. However, if there’s a second subject in the consequence clause, it goes right before 就 jiù — not after it.

一旦yídàn你nǐ学会xuéhuì中文zhōngwén，你的nǐde未来wèilái就jiù多duō了le700万wàn个ge工作gōngzuò机会jīhuì
Once you learn Chinese, you’ll have 7 million more jobs in the future.
Second subject 你的未來 sits right before 就.
一旦yídàn你nǐ迟到chídào了le，就jiù不能bùnéng进入jìnrù考场kǎochǎng
If you are late, you won’t be able to enter the exam room.
你nǐ一旦yídàn错过cuòguò了le火车huǒchē，就jiù得děi等到děngdào明天míngtiān了le
If you miss the train, you will have to wait until tomorrow.
你nǐ一旦yídàn养yǎng了le一只yìzhī狗gǒu就jiù会huì习惯xíguàn有yǒu狗gǒu的de生活shēnghuó，然后ránhòu再zài也yě离不开líbùkāi狗gǒu
Once you have a dog, you will get used to having a dog in your life, and then you can never leave dogs behind.
黄金huángjīn一旦yídàn上涨shàngzhǎng，美金měijīn往往wǎngwǎng就jiù会huì往wǎng下xià跌diē
Once gold goes up, the dollar tends to go down.
Second subject 美金 sits right before 就, even with the adverb 往往 in between.
你nǐ一旦yídàn感染gǎnrǎn了le新冠xīnguān肺炎fèiyán，就jiù只zhǐ能néng待dāi在zài家裡jiālǐ
Once you catch COVID-19, you can only stay at home.

2 Common Mistakes

A second subject in the consequence clause belongs right before 就 jiù, not after it.

❌
黄金huángjīn一旦yídàn上涨shàngzhǎng，就jiù美金měijīn往往wǎngwǎng会huì往wǎng下xià跌diē
✅
黄金huángjīn一旦yídàn上涨shàngzhǎng，美金měijīn往往wǎngwǎng就jiù会huì往wǎng下xià跌diē
The second subject 美金 needs to come before 就 jiù, matching normal Chinese word order (Subject + 就 + Verb) — putting it after 就 breaks the sentence.

3 Practice

Translate each sentence into Chinese, then tap the card to check your answer.

01Once you have an idea, you should implement it thoroughly.
一旦yídàn有yǒu想法xiǎngfǎ就jiù应该yīnggāi彻底chèdǐ施行shīxíng
👆 Tap to reveal
02Once you hesitate, you will miss the opportunity to succeed.
你nǐ一旦yídàn犹豫yóuyù就jiù会huì错过cuòguò成功chénggōng的de机会jīhuì
👆 Tap to reveal
03Bravely pursue your dreams while you are young! Because once you are old, you will find many things you would like to do but can not do.
趁chèn年轻niánqīng时shí勇敢yǒnggǎn地de追寻zhuīxún梦想mèngxiǎng吧ba！因为yīnwèi一旦yídàn你nǐ老lǎo了le，你nǐ就jiù会huì发现fāxiàn很多hěnduō事shì想xiǎng做zuò也yě做不到zuòbúdào了le
👆 Tap to reveal
04Once you make a promise, you have to follow through.
一旦yídàn你nǐ答应dāyìng了le，就jiù要yào做zuò到dào
👆 Tap to reveal
05Once you start exercising, you’ll find your body getting healthier.
你nǐ一旦yídàn开始kāishǐ运动yùndòng，就jiù会huì发现fāxiàn身体shēntǐ越来越yuèláiyuè健康jiànkāng
👆 Tap to reveal
06Once a typhoon comes, school will be cancelled.
一旦yídàn台风táifēng来lái了le，学校xuéxiào就jiù会huì停课tíngkè
👆 Tap to reveal
07Once this secret is told, it can never be taken back.
这个zhège秘密mìmì一旦yídàn说shuō出去chūqù，就jiù再也zàiyě收不回来shōubùhuílái了le
👆 Tap to reveal
08Once you give up, there will be no more chances.
一旦yídàn你nǐ放弃fàngqì了le，就jiù再也zàiyě没有méiyǒu机会jīhuì了le
👆 Tap to reveal
09Once housing prices drop, more people will buy homes.
房价fángjià一旦yídàn下跌xiàdiē，买mǎi房fáng的de人rén就jiù会huì变biàn多duō
👆 Tap to reveal
10Once you get used to staying up late, it’s hard to adjust your body back to a normal schedule.
一旦yídàn习惯xíguàn了le熬夜áoyè，身体shēntǐ就jiù很hěn难nán调tiáo回huí正常zhèngcháng作息zuòxí
👆 Tap to reveal

Related Grammar

→就 jiù Chinese Grammar

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