5 · Expressions (level 5)
Four-character expressions: chéngyǔ in a sentence
fixed idioms and how they behave
How the four-syllable idioms are built, where they go in a sentence, and why they never take hěn.
A 成语 is a fixed expression, nearly always of four characters, that works as a single unit. Many come from classical texts and old stories and keep classical grammar inside them; some can be read character by character — 自言自语, “self speak self say”, talking to oneself — and some cannot be understood without the story behind them.
Because a chengyu is one block, nothing can be added, removed or moved inside it, and it rarely takes a degree word: many already contain their own intensity. 一模一样 is “exactly alike”, so 很 in front of it has nowhere to go. In a sentence most chengyu behave like one of three word classes: a predicate on their own (街上人山人海, “the street was packed”), an adverbial with 地 before a verb, or an attribute with 的 before a noun.
Their inner structure follows a few patterns that are worth recognising: parallel pairs such as 一…一… and 不…不…; numbers used as images, 七上八下, “seven up, eight down”, for a fluttering heart; and classical function words — 而 for “and yet”, 之 for “of”, 无 for “without”.
Educated Chinese uses them constantly, in speech as well as writing, and one well-chosen chengyu can replace a whole clause. But they carry weight: a paragraph with one in every sentence sounds like a speech or a school essay. The best way to learn them is never from a list, always inside a sentence.
The form
| as a predicate | 街上人山人海。 |
| as an adverbial, with de | 他一心一意地学习。 |
| before a noun, with de | 这是一个与众不同的设计。 |
| as a verb phrase | 他做事总是半途而废。 |
| the pattern bù … bù … | 不知不觉天就黑了。 |
The rules one by one
The form this topic is aboutThe word that calls for it
A chengyu is one fixed unit: no word can be added, taken out or moved.
这对双胞胎长得一模一样。These twins look exactly alike.
Most can be a predicate on their own, without 很 or 是.
节日的时候，公园里人山人海。During the holidays the park is packed with people.
Before a verb many take 地, before a noun many take 的.
孩子们兴高采烈地跑了出去。The children ran out in high spirits.
Their inner grammar is often classical: 而 for “and yet”, 无 for “without”, paired 不.
他的计划半途而废了。His plan was abandoned halfway.
Use them where they fit, not in every sentence: a chengyu adds weight, and too many sound like a speech.
这家饭馆的菜味道与众不同。The food at this restaurant has a taste all its own.
A closer look
Where they come from
Many chengyu are a story compressed into four characters. 画蛇添足, “draw a snake, add feet”, goes back to a contest in which the first person to finish drawing a snake would win a cup of wine; one man finished first, decided to add feet, and lost — because snakes have none. The four characters now mean spoiling something by doing too much.
Others are images that need no story: 胸有成竹, “to have the finished bamboo in one’s chest”, is a painter who sees the picture before drawing it — to have a plan already worked out. Reading the characters one by one, and then asking what picture they make, unlocks a surprising number of them.
How to spot it
- 地
- 的
- 一…一…
- 不…不…
- 而
- 无
Example sentences
做事不要三心二意。Don’t do things half-heartedly.
我们聊着聊着，不知不觉就到了半夜。We chatted on and on, and before we knew it, it was midnight.
他爱喝茶是众所周知的。It is common knowledge that he loves tea.
第一次上台，他心里七上八下的。Going on stage for the first time, he was a bundle of nerves.
这个问题很复杂，不能一概而论。This is a complicated question; you can’t generalise.
他俩合作了十年，配合得天衣无缝。The two of them have worked together for ten years and complement each other seamlessly.
6 more example sentences
她说话总是直截了当。She always speaks very directly.
这次比赛他们赢得轻而易举。They won this match with ease.
你的帮助对我来说是雪中送炭。Your help came to me just when I needed it most.
他画完了还要加几笔，结果画蛇添足。He had finished the picture but insisted on adding a few strokes, and only spoiled it.
别担心，这件事他早就胸有成竹了。Don’t worry — he has had a plan for this all along.
两个人见面后一见如故，聊了一个晚上。The two of them got on like old friends from the moment they met, and talked all evening.
Worth knowing (1)
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Reading one character by character
Some chengyu translate themselves once each character is known. 自言自语 is “self speaks, self talks”: talking to oneself. The parallel pattern — two halves that say nearly the same thing — is one of the commonest shapes, and it is a useful first guess for an unknown idiom.
他一边走一边自言自语。He talked to himself as he walked.
The trap English speakers fall into
Watch out
Chinese adjectives as predicates usually need 很, so learners add it here too. But a chengyu is not a bare adjective: 一模一样 already means “exactly the same”, and an extra “very” is like saying “very identical” in English. Most chengyu stand as predicates on their own.
A chéngyǔ is one block: do not open it, do not add hěn to it, and do not use one in every sentence.
Your turn
8 exercises on this topic. Your answers are checked in the browser; none of them leaves your device.