不是 (bú shì): It Is Not | Chinese (Mandarin) Grammar

To say something is not what it seems, you negate the copula 是 (shì, "to be") with 不, giving 不是 (bú shì). 我不是学生 ("I'm not a student"), 这不是我的 ("this isn't mine"). The character 是 is one of the first words learners meet, and its negation is refreshingly regular — one form, one rule: 是 is negated only by 不, never by 没. The traps aren't in 是 itself but in overusing it, because English "is/are/am" covers far more ground than Chinese 是. This page draws those boundaries and introduces the contrastive frame 不是…而是.

The basic pattern: 不 + 是 + noun

是 is a linker between two nouns or noun phrases that names an identity: A 是 B means "A is (the same as / an instance of) B." Its negative simply removes that link:

我不是学生，我是老师。

wǒ bú shì xuésheng, wǒ shì lǎoshī

I'm not a student — I'm a teacher. (neutral)

这不是我的，是我朋友的。

zhè bú shì wǒ de, shì wǒ péngyou de

This isn't mine — it's my friend's. (informal)

他不是中国人，是韩国人。

tā bú shì Zhōngguó rén, shì Hánguó rén

He isn't Chinese — he's Korean. (neutral)

Note two things baked into every example. First, 是 keeps its sandhi pronunciation bú shì — because 是 is 4th tone, 不 rises to bú (see 不 sandhi). Second, there is a noun on both sides: 我 / 学生, 这 / 我的, 他 / 中国人. That two-noun shape is the signature of 是 — and the clue to when not to use it.

What 不是 does NOT negate

Because English "be" is so greedy — "he is tall," "she is at home," "I am hungry" — learners over-apply 是. But Chinese uses 是 only for noun-to-noun identity. Three things English handles with "be" take a completely different negation in Chinese:

To negate…	Use	Example	Not…
identity (是 + noun)	不是	他不是医生	—
a quality (adjective)	不 + adjective	他不高	✗ 他不是高
a location (在)	不在	他不在家	✗ 他不是在家
possession / existence (有)	没有	我没有钱	✗ 我不是有钱

The reason adjectives reject 是 is that a Chinese adjective is already a verb ("to be tall," "to be expensive") — it doesn't need a separate "be." So the negation attaches straight to it: 不高, not 不是高. See adjectives as stative verbs.

今天不是很冷，你穿这件就行。

jīntiān bú shì hěn lěng, nǐ chuān zhè jiàn jiù xíng

It's not very cold today — this one will do. (informal)

Read that carefully: 不是 is fine here because it negates the whole assessment 很冷 in a softening, "it's not that it's cold" way — but the plain everyday negative is still 今天不冷 (bù lěng), with no 是. Reach for bare 不 + adjective by default.

不是…而是: not X, but Y

不是 is the hinge of Chinese's main corrective structure: 不是 A，而是 B — "it's not A, but rather B." You deny one thing and supply the correction in the same breath:

我要的不是这个，而是那个。

wǒ yào de bú shì zhège, ér shì nàge

What I want isn't this one, but that one. (neutral)

他不是不想去，而是没时间。

tā bú shì bù xiǎng qù, ér shì méi shíjiān

It's not that he doesn't want to go — it's that he doesn't have the time. (informal)

That second sentence is a small masterclass in negation: 不是 (deny the claim) … 不想 (habit/desire → 不) … 而是 (correction) … 没时间 (existence → 没). Three negators, each doing its own job. A sibling frame, 不是 A 就是 B ("if not A, then B / either A or B"), is covered on the 不是…而是 / 就是 page.

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是 is a bridge between two things that are the same; 不是 tears the bridge down. If there's no second noun on the far side, you don't want 不是 at all — you want plain 不 (before an adjective or verb) or 没 (before 有 or a completed action).

不是…吗: the rhetorical question

Wrap 不是 in a 吗-question and you get a rhetorical effect — not a real question but a pointed reminder, roughly English "Isn't it the case that…?" / "Didn't you…?":

你不是说过了吗？怎么又问？

nǐ bú shì shuō guo le ma? zěnme yòu wèn?

Didn't you already say so? Why are you asking again? (informal)

这不是很好吗？大家都同意。

zhè bú shì hěn hǎo ma? dàjiā dōu tóngyì

Isn't this great? Everyone agrees. (informal)

The speaker isn't seeking information — they're asserting the opposite of the negative, confidently. It's one of the most natural, high-frequency uses of 不是 in conversation.

不是 as a standalone 'no'

Finally, 不是 on its own works as a flat contradiction — "no," "that's not it" — used to correct a wrong assumption before you go on:

不是，你听我说，我不是那个意思。

bú shì, nǐ tīng wǒ shuō, wǒ bú shì nàge yìsi

No — hear me out, that's not what I meant. (informal)

Chinese has no all-purpose "yes/no" word; you answer by echoing or negating the verb of the question. When the question hinges on 是, the "no" answer is simply 不是.

Common Mistakes

1. Putting 是 in front of an adjective. Adjectives are already verbs; they take bare 不.

❌ 他不是高。

Incorrect — an adjective needs no 是; say 他不高.

✅ 他不高。

tā bù gāo

He isn't tall.

2. Negating 是 with 没. 是 is an identity verb, not 有 or an event — it only ever takes 不.

❌ 我没是学生。

Incorrect — there is no 没是; the copula takes 不: 不是.

✅ 我不是学生。

wǒ bú shì xuésheng

I'm not a student.

3. Using 不是 for location. "Not at home" uses 在, negated to 不在 — not 不是在.

❌ 他不是在家。

Incorrect — location uses 在; say 他不在家.

✅ 他不在家。

tā bú zài jiā

He isn't home.

4. Pronouncing bù shì. Because 是 is 4th tone, 不 rises: it's bú shì, not bù shì.

❌ 不是 pronounced bù shì

Incorrect — 是 is 4th tone, so 不 rises to bú: bú shì.

✅ 不是 pronounced bú shì

bú shì

is not — 不 rises before the 4th-tone 是.

Key Takeaways

Negate identity with 不 + 是: 我不是学生, 他不是中国人. 是 takes only 不 — never 没是.
是 links two nouns; don't use 不是 for adjectives (他不高), locations (不在), or possession (没有).
Always pronounced bú shì — the 不 rises before the 4th-tone 是.
不是 A，而是 B = "not X, but Y"; 不是…吗? is a rhetorical "isn't it…?"; bare 不是 = "no, that's not it."

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