Inserting 是 Before an Adjective (*她是高 → 她很高) | Chinese (Mandarin) Grammar

"She is tall." "The weather is good." "This is expensive." Every one of those English sentences has an is in it, so when you build the Chinese version, your hand reaches for 是 (shì): 她是高, 天气是好. This is wrong every single time. A Chinese adjective is not a bare description waiting for a verb — it is the verb. 高 doesn't mean "tall," it means "to be tall"; 好 means "to be good." The "is" you're trying to add is already baked into the word, so 是 has no job to do. The correct plain form uses a small, almost meaningless linker 很 instead: 她很高. The deep story is at adjectives are stative verbs; this page is here to break the 是 habit fast.

The error, and the fix

❌ 她是高。

Incorrect — 高 already means 'to be tall', so no 是: 她很高。

✅ 她很高。

tā hěn gāo

She's tall. (neutral) — 很 links subject and adjective; no copula.

❌ 天气是好。

Incorrect — an adjective predicate takes 很, not 是: 天气很好。

✅ 今天天气很好。

jīntiān tiānqì hěn hǎo

The weather's nice today. (informal) — 好 is the verb; 很 fills the linker slot.

What 是 is actually for: linking two nouns

是 is a copula between two nouns — "A is B," where both A and B are things: 他是老师 "he is a teacher," 这是我的书 "this is my book." An adjective isn't a noun, so it never follows 是. Keep the two patterns in separate mental boxes:

Predicate type	Pattern	Example
Noun ("A is B")	Subject + 是 + noun	他是医生 (he is a doctor)
Adjective ("A is tall")	Subject + 很 + adjective	他很高 (he is tall)

他是医生，工作很忙。

tā shì yīshēng, gōngzuò hěn máng

He's a doctor, and work keeps him busy. (neutral) — 是 before the noun 医生, 很 before the adjective 忙, in one breath.

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Quick test: can you swap the word after "is" for another noun? "She is a doctor / my friend" → yes, so use 是. "She is tall / tired / happy" → no, it's a quality, so drop 是 and use 很. The copula lives at 是 as the copula.

The over-correction: dropping 很 too

Once learners hear "no 是 before adjectives," many strip the sentence down to bare 她高 — and that sounds incomplete or pointedly contrastive to a native ear, as if you're about to add "…but her sister is short." A plain, neutral statement needs the linker 很 in the slot. So the target isn't "no 是 and no 很" — it's "swap 是 for 很."

❌ 我累。

Sounds clipped/contrastive on its own — a plain statement needs 很: 我很累。

✅ 我很累，想早点睡。

wǒ hěn lèi, xiǎng zǎo diǎn shuì

I'm tired, I want to sleep early. (informal) — 很 makes it a complete, neutral statement.

Crucially, this 很 is not "very." 我很累 just means "I'm tired," not "I'm very tired." It's a grammatical placeholder, not an intensifier — a trap covered in 很 misread as 'very' and the default 很.

When 是 and an adjective do meet: 是…的

There's one real construction where 是 sits near an adjective, and learners sometimes cite it to justify 她是高 — but it's a different structure. In 是…的, the adjective is nominalized by 的 into "a … one," so 是 is once again linking two noun-like things:

这个是新的，那个是旧的。

zhège shì xīn de, nàge shì jiù de

This one's new, that one's old. (informal) — 新的 = 'a new one'; 是 links 这个 to that noun-phrase, not to a bare adjective.

Use 是…的 for identifying or contrasting ("which one? the new one"), not for plainly describing something. For a plain description, it's still 很: 这个手机很新 "this phone is new."

Common Mistakes

1. Copying "is" as 是. The English is is already inside the adjective.

❌ 这个是贵。

Incorrect — describe with 很 or 太…了: 这个很贵 / 这个太贵了。

✅ 这个太贵了！

zhège tài guì le!

This is too expensive! (informal) — 太…了 for a strong degree, still no 是.

2. Keeping 是 and adding 很 as well. Pick one — and for adjectives it's 很.

❌ 他是很聪明。

Incorrect — drop 是: 他很聪明。

✅ 他很聪明。

tā hěn cōngming

He's clever. (neutral) — 很 alone links to the adjective.

3. Negating an adjective with 不是 instead of 不. An adjective is negated by 不 directly.

❌ 今天不是冷。

Incorrect — negate the adjective with 不, not 不是: 今天不冷。

✅ 今天不冷。

jīntiān bù lěng

It's not cold today. (neutral) — 不 + adjective; 不是 would negate a noun.

Key Takeaways

A Chinese adjective is a stative verb: 高 = "to be tall," so it needs no 是.
是 links two nouns ("A is B"); a bare adjective is not a noun, so 是 never precedes it.
Don't over-correct into bare 她高 — a plain statement takes the linker 很: 她很高.
That default 很 is not "very" — it's an empty placeholder.
是…的 (这个是新的) is a separate, nominalizing structure for identifying/contrasting, not for plain description; negate an adjective with 不 (不冷), not 不是.

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