How to Say “Once / Formerly” with 曾经 (céngjīng)
曾经 (céngjīng) is the adverb for “once (upon a time) / formerly / used to.” It comes before the verb and marks that something was the case in the past, usually with the sense that it isn't now. With action verbs it pairs with 过 (我曾经去过西藏), and with 是 / 在 / 有 it takes no 过 (他曾经是我老板). Its negative is simply 没……过, never 没曾经.
Why this trips learners up
曾经 (céngjīng) is the adverb for “once (upon a time) / formerly / used to.” It sits before the verb and adds the sense that something was the case at some point in the past, very often with the flavour that it isn't any more. That “no longer” colour is what makes 曾经 more than a neutral past marker: 这栋楼曾经是一家医院 (“this building was once a hospital,” implying it isn't now), 她曾经有一头长发，现在剪短了 (“she once had long hair; now she's cut it short”). It frequently pairs with 过.
With action verbs and adjectives, use 曾经 + Verb + 过. Here 曾经 nearly always leans on 过: 我曾经去过西藏 (“I once went to Tibet”), 他曾经当过老师 (“he was once a teacher”). Adjectives take 过 too: 这个小镇曾经繁华过 (“this town was once prosperous”), 我们都曾经年轻过 (“we were all young once”). Occasionally, for a specific completed action rather than a general experience, 曾经 pairs with 了 instead: 为了梦想，他曾经放弃了稳定的工作 (“for his dream, he once gave up a stable job”).
With the existence verbs 是 / 在 / 有, drop the 过. These describe states rather than actions, so 曾经 alone places them in the past and no 过 is needed: 他曾经是我老板 (“he was once my boss”), 市政府曾经在我们家旁边 (“the city government was once next to our house”), 她曾经有一个西班牙男朋友 (“she once had a Spanish boyfriend”). Saying 曾经是过 is a mistake; keep 是 / 在 / 有 bare.
The last thing to nail is the negative, because it catches everyone: you don't negate 曾经. Since this is about past actions, the negative is simply 没……过, with 曾经 dropped entirely: 我没去过日本 (“I've never been to Japan”). 没曾经 and 不曾经 are both wrong. (In formal writing you may see 不曾 / 未曾 + Verb + 过, but not in speech.) And keep 曾经 apart from plain 过, laid out in the comparison below: 过 on its own marks present-relevant experience, “have you ever…,” with no “no longer” colour, and it can't sit before 是 / 在 / 有. 曾经 supplies the “used to”; 过 supplies the “have done”; the two often team up as 曾经…过.
The structure
Colour key
Each colour marks one grammatical role — and the same colour means the same role on every page in the Lab.
Examples in context
Real-world sentences, easiest first. Toggle pinyin or the translation, tap any word to see its role, or play the audio.
Tap a word to see its grammatical role.
wǒ 我 Subject céngjīng 曾经 Pattern qù 去 Verb guo 过 Function word Xīzàng 西藏 Object
I once went to Tibet (曾经 + verb + 过 + object).
tā 他 Subject céngjīng 曾经 Pattern dāng 当 Verb guo 过 Function word lǎoshī 老师 Object
He was once a teacher (曾经 + verb + 过).
zhè dòng lóu 这栋楼 Subject céngjīng 曾经 Pattern shì 是 Verb yì jiā yīyuàn 一家医院 Object
This building was once a hospital (曾经 + 是, no 过).
zhège xiǎozhèn 这个小镇 Subject céngjīng 曾经 Pattern fánhuá 繁华 Adjective guo 过 Function word
This town was once prosperous (曾经 + adjective + 过).
wèile mèngxiǎng 为了梦想， Other tā 他 Subject céngjīng 曾经 Pattern fàngqì 放弃 Verb le 了 Function word wěndìng de gōngzuò 稳定的工作 Object
For his dream, he once gave up a stable job (曾经 + verb + 了, a specific act).
tā 她 Subject céngjīng 曾经 Pattern yǒu 有 Verb yì tóu chángfà 一头长发 Object xiànzài jiǎn duǎn le 现在剪短了 Other
She once had long hair; now she's cut it short (曾经 + 有, no 过, and no longer).
zhè wèi lǎorén 这位老人 Subject céngjīng 曾经 Pattern zài zhè zuò chéngshì 在这座城市 Place shēnghuó 生活 Verb guo 过 Function word hěn duō nián 很多年 Time
This old man once lived in this city for many years (曾经 + 在… + verb + 过 + duration).
zhè wèi zuòjiā 这位作家 Subject céngjīng 曾经 Pattern huòdé 获得 Verb guo 过 Function word hěn duō jiǎng 很多奖 Object
This writer once won many awards (曾经 + verb + 过, a weightier record).
Common mistakes
Why it happens: You don't negate 曾经. To say “I've never done X,” drop 曾经 and just use 没……过: 我没去过日本 (“I've never been to Japan”). 没曾经 and 不曾经 are wrong. In formal writing you can use 不曾 / 未曾 + Verb + 过, but not in everyday speech.
Why it happens: The existence verbs 是 / 在 / 有 don't take 过, so it's 他曾经是我的老板 (“he was once my boss”), not 曾经是过. 过 attaches to action verbs and adjectives; 是 / 在 / 有 describe states, and 曾经 alone is enough to place them in the past.
Why it happens: 曾经 is only the adverb; with an action verb it needs 过 (or 了) to complete the “once did” meaning. 我曾经去过西藏 is right; 我曾经去西藏 is left hanging. Pair 曾经 with 过 for an experience, or 了 for a specific completed action.
Compare & contrast
| 曾经 céngjīng (adverb “once / formerly”: it was so in the past, usually not now) | 过 guo (aspect suffix “have done”: present-relevant experience) | The difference |
|---|---|---|
| 他曾经是我的老板tā céngjīng shì wǒ de lǎobǎn = “he was once my boss (not any more)”; 曾经 works with 是, and 是过 is impossible | 你吃过日本菜吗？nǐ chī guo Rìběn cài ma? = “have you ever had Japanese food?”; plain 过 marks the experience you now carry, and it attaches only to action verbs | 他曾经是我的老板 means “he was once my boss (not any more),” and 曾经 happily takes 是 (是过 is impossible). 你吃过日本菜吗？ means “have you ever had Japanese food?”, where plain 过 marks the experience you now carry and attaches only to action verbs. 曾经 can sit before 是 / 在 / 有; 过 cannot. |
| 我曾经喜欢过他wǒ céngjīng xǐhuan guo tā = “I once liked him (in the past)”; 曾经 and 过 team up, adding the “formerly, no longer” colour | 我去过北京wǒ qù guo Běijīng = “I’ve been to Beijing”; plain 过 states a life experience up to now, with no “no longer” implication | 我曾经喜欢过他 means “I once liked him (in the past),” 曾经 and 过 teaming up to add the “formerly, no longer” colour. 我去过北京 means “I've been to Beijing,” plain 过 stating a life experience up to now with no “no longer” implication. They often combine, but 曾经 supplies the “used to,” 过 the “have done.” |
Try it yourself
Say “I once studied French for three years.” Use 曾经 + verb + 过.
Related patterns
Quick reference card
How to Say “Once / Formerly” with 曾经 (céngjīng) grammar.merrymandarin.com A pocket summary — print it and keep it by your desk.