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HSK 7-9 Judgment Adverb: 乃 (nǎi)
At the advanced HSK 7-9 level, 乃 (nǎi) is classified as a judgment adverb used in formal, literary, and idiomatic contexts to affirm identity, definition, or essence.
诚信乃立身之本。
Uses 乃 directly before a classical-style four-character nominal predicate (立身之本) to state a moral maxim.
× 这个手机乃不是我的。
For this ordinary denial of ownership, 乃不是 is not natural contemporary wording. Remove 乃 as in the next example. This does not establish a ban on all negative content or on daily-life objects in literary language.
Corrected example: 这个手机不是我的。
Read the full explanation and examples
Core Meaning and Syllabus Classification
The supplied HSK 7-9 outline lists 乃 under 判断副词, “judgment adverbs.” This lesson follows that label and focuses on 乃 meaning “is / is indeed” in statements of identity or definition. It is typical of literary prose, maxims and formal narration. Other reference works may assign a different word-class label to this use; the label alone does not determine how to build a sentence.
In 乃是, 是 introduces the identity or definition and 乃 adds literary or emphatic force. The pattern 乃 + noun phrase also occurs, as in 失败乃成功之母. Learn both patterns as ways to identify or define a subject with a marked literary tone.
Core Sentence Structures
When expressing judgment or definition, 乃 appears in two primary patterns. The choice between them depends on rhythm and how classical or modern the surrounding sentence is.
乃 directly before a noun phrase is common in concise literary statements and maxims. The examples have compact nominal phrases, but there is no requirement that the entire sentence have four characters. Rhythm is a style consideration, not a word-count test.
诚信乃立身之本。
Uses 乃 directly before a classical-style four-character nominal predicate (立身之本) to state a moral maxim.
失败乃成功之母。
A well-known proverb where 乃 links two brief noun phrases with strong affirmative force.
乃是 also fits longer statements with modified noun phrases. It can add explanatory emphasis, as in the Silk Road example. Sentence length alone does not require 乃是 or make 乃 impossible.
此地乃是古代丝绸之路的重要枢纽。
Uses 乃是 in formal historical commentary before a longer modern noun phrase.
Register, Nuance, and Useful Contrasts
Choose 乃 for a literary, rhetorical or deliberately old-fashioned effect. Ordinary 是 is the default for a neutral conversation. A daily-life object is not grammatically barred from a sentence with 乃; using it about such an object may sound theatrical or humorous.
- 是 (shì) is the usual neutral choice for identifying or classifying something in speech and writing.
- 乃是 (nǎi shì) or 乃 (nǎi) adds a solemn, literary, or emphatic tone ('is indeed', 'is none other than'), often highlighting the fundamental nature or origin of something.
- 为 (wéi), in its judgment use, is also common in written definitions and statements. It is not interchangeable with every occurrence of 是. Compared with a plain definition using 为, 乃 can give a stronger literary or rhetorical effect.
Compare the following pair of sentences. Both are grammatically sound, but the first uses 乃是 to frame the shop's history with narrative gravity, while the second uses 是 for a plain factual statement.
那家小店乃是老板白手起家的起点。
Uses 乃是 to add narrative emphasis and formality when highlighting a significant origin.
那家小店是老板白手起家的起点。
Neutral baseline using 是 without the literary emphasis of 乃.
Register and Natural Negative Wording
For an ordinary denial of ownership, use 这部手机不是我的 or 这部手机并不是我的. 乃不是 is not the normal contemporary way to make this statement. Keep this wording recommendation separate from a claim that 乃 can never occur near a negative expression: its other literary meanings and the structure of the whole clause matter.
The phone example below is an unsuitable combination for the intended neutral statement. Removing 乃 fixes the wording without changing the owner, the object or the negative meaning. Its problem is not that phones are an impermissible topic.
× 这个手机乃不是我的。
For this ordinary denial of ownership, 乃不是 is not natural contemporary wording. Remove 乃 as in the next example. This does not establish a ban on all negative content or on daily-life objects in literary language.
Corrected example: 这个手机不是我的。
这个手机不是我的。
The ordinary negative wording preserves the intended meaning: the phone does not belong to the speaker.
乃 has other literary senses, including “then / only then” and “your,” and it is part of the word 乃至 (nǎizhì, “even / as far as”). Those uses are not all judgments of identity. Here, focus on the judgment patterns 乃 + noun phrase and 乃是 + noun phrase.
Frequently asked questions
Should I use 乃 in the spoken part of an advanced Chinese exam?
Use it when a proverb, literary quotation or deliberate rhetorical emphasis fits what you are saying. It is not required to demonstrate advanced speaking ability. In an ordinary explanation, 是 or 就是 will usually sound more natural. This is guidance on expression, not a rule about an examiner’s marking.
Is there a meaning difference between 乃 and 乃是?
Both can express “is / is indeed” in literary judgment statements. 乃 alone is common in compact formulations, while 乃是 explicitly includes 是 and also works in longer statements. The choice reflects the whole phrasing and tone, not a fixed sentence-length boundary.
Does 乃 always act as a judgment adverb?
No. This lesson follows the outline’s judgment-adverb label, but 乃 also has other literary meanings, and word-class analysis varies across reference works. The meaning and construction must be read in context.
