English "be" does two jobs that Chinese keeps strictly apart. "I am a student" links you to a noun — and Chinese does that with 是 (shì): 我是学生. But "I am busy" links you to an adjective — and here Chinese uses no verb at all: 我很忙 (wǒ hěn máng), literally "I very busy." Because English fuses the two, beginners reach for 是 in both cases and produce 我是忙 or 她是高 — very possibly the single most common mistake in beginner Chinese. This page draws the boundary sharply: when a noun follows, use 是; when an adjective follows, drop 是 and reach for a degree word like 很. It also handles the one honest exception, the stressed 是. For the broader map of where 是 belongs, see the copula 是 overview.
Two predicate types, two structures
The whole rule fits in one table. What follows the subject decides everything:
| Predicate is… | Structure | Example | Meaning |
|---|---|---|---|
| a noun | Subject + 是 + Noun | 我是老师 (wǒ shì lǎoshī) | I am a teacher |
| an adjective | Subject + 很/非常/太…了 + Adj | 我很累 (wǒ hěn lèi) | I am tired |
If you can put "a / an / the" in front of the English word, it's a noun — use 是. If the English word is a quality (tall, busy, cold, good), it's an adjective — no 是.
我是老师，她是医生。
wǒ shì lǎoshī, tā shì yīshēng
I'm a teacher, she's a doctor. (neutral) — nouns on both sides, so 是.
今天很热，别忘了带瓶水。
jīntiān hěn rè, bié wàng le dài píng shuǐ
It's hot today — don't forget to bring a bottle of water. (informal) — 热 is an adjective, no 是.
他很聪明，就是有点儿懒。
tā hěn cōngming, jiùshì yǒudiǎnr lǎn
He's smart — just a bit lazy. (informal) — both 聪明 and 懒 are adjective predicates, no copula anywhere.
Why there is no 是: adjectives are stative verbs
The deep reason is that a Chinese adjective is not a bare quality waiting for a verb — it is the verb. 高 (gāo) doesn't mean "tall," it means "to be tall"; 忙 doesn't mean "busy," it means "to be busy." The "be" is already baked in. So putting 是 in front would be like saying "she is is-tall" — one "be" too many. This is the core of the adjectives-are-verbs idea, and it is why Chinese needs no copula here at all.
What normally sits in front of the adjective instead is a degree adverb, most often 很 (hěn). In a plain statement, 很 is not real emphasis — it's a near-empty default linker, so light that 她很高 just means "she's tall," not "she's very tall." A bare adjective with nothing in front (她高) sounds unfinished or contrastive, as if a "but…" is coming. That default role of 很 has its own page: the default 很.
这个菜很好吃，你尝尝。
zhège cài hěn hǎochī, nǐ chángchang
This dish is delicious, have a taste. (informal) — 好吃 is a stative verb; 很 is the neutral link, not 'very'.
她很高，打篮球很有优势。
tā hěn gāo, dǎ lánqiú hěn yǒu yōushì
She's tall, which is an advantage in basketball. (neutral) — 高 stands alone as the predicate; no 是.
Where the 是 comes from: English transfer
It helps to see why the wrong 是 feels so natural. English says "she is tall" and "she is a student" with the identical word, so learners map both onto 是. But Chinese already spent its "be" inside the adjective. The fix is not to translate "is" — it's to remember that the adjective is the whole predicate, and to give it a degree adverb instead of a copula.
我很高兴认识你。
wǒ hěn gāoxìng rènshi nǐ
I'm glad to meet you. (polite) — 高兴 is an adjective/stative verb; 我是高兴 would be wrong.
外面很冷，多穿一件。
wàimiàn hěn lěng, duō chuān yí jiàn
It's cold outside — put on an extra layer. (informal) — weather adjectives take no 是.
The one real exception: stressed, contrastive 是
Now the honest wrinkle. 是 can appear before an adjective — but only as a stressed, contrastive "it IS so," never in a neutral description. 他是很高 (with audible stress on 是) means "he is tall (I grant you / as it happens)," setting up a concession or a contrast. This is the emphatic 是, a different construction from the plain predicate.
他是很高，可惜不喜欢打篮球。
tā shì hěn gāo, kěxī bù xǐhuan dǎ lánqiú
He IS tall — it's just a shame he doesn't like basketball. (informal) — stressed, concessive 是, not a plain 'he is tall'.
There is also a related pattern that looks like "是 + adjective" but isn't: the 是…的 identity frame. In 她是高的，不是矮的 ("she's a tall one, not a short one"), 高的 is really a noun-like phrase ("a tall one") formed with 的 — so 是 is doing its normal job of linking to a noun, not modifying a bare adjective. Use this only when you truly mean an emphatic identity ("she's the tall type"), not for ordinary "she is tall." That 的-nominalization and the circumstance-highlighting 是…的 construction share the same machinery.
她是高的那个，不是矮的。
tā shì gāo de nàge, bú shì ǎi de
She's the tall one, not the short one. (informal) — 高的 is nominalized ('the tall one'), so 是 links to a noun phrase.
这不是免费的，要收钱。
zhè bú shì miǎnfèi de, yào shōu qián
This isn't free, there's a charge. (neutral) — 免费的 ('a free one') is noun-like, so 是/不是 fits.
Common Mistakes
1. Putting 是 before an adjective. The number-one beginner error. Adjectives are stative verbs and take 很, not 是.
❌ 我今天是忙。
Incorrect — 忙 is an adjective/stative verb; drop 是. Say 我今天很忙.
✅ 我今天很忙。
wǒ jīntiān hěn máng
I'm busy today. — adjective predicate with default 很.
2. Using 是…的 for a plain description. 她是高的 as a neutral "she is tall" is wrong — that frame means "she's a tall one." Plain description uses 很.
❌ 她是高。
Incorrect — never 是 before a bare adjective. Say 她很高.
✅ 她很高。
tā hěn gāo
She's tall. — the neutral way to describe a quality.
3. Dropping the degree adverb in a plain statement. A naked adjective (她高) sounds contrastive or incomplete; a neutral statement needs 很 (or another degree word).
❌ 这个房间大。
Incomplete as a plain statement — sounds like a half-finished comparison. Add 很.
✅ 这个房间很大。
zhège fángjiān hěn dà
This room is big. — 很 gives the adjective a neutral link.
4. Using 是 for feelings and states. Emotions and conditions are adjectives too — 高兴, 累, 饿 all reject 是.
❌ 我是很高兴。（as a plain statement）
Incorrect as a neutral statement — 高兴 needs no 是. Say 我很高兴.
✅ 我很高兴。
wǒ hěn gāoxìng
I'm happy. — the adjective is its own predicate.
Key Takeaways
- Noun after the subject → 是 (我是学生). Adjective after the subject → no 是 (我很忙).
- Adjectives are stative verbs (高 = "to be tall"), so the "be" is already inside them; adding 是 doubles it up.
- The default link before an adjective is 很 — a near-empty linker, not "very." A bare adjective sounds contrastive.
- The only time 是 precedes an adjective is a stressed, contrastive 是 (他是很高 = "he IS tall, granted"). The 是…的 frame is really 是 + a noun-like 的-phrase, not 是 + adjective.
- If you can say "a/the _" in English, it's a noun (use 是); if it's a quality, it's an adjective (use 很).
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- The Copula 是 (shì): A is BHSK 1 — 是 (shì) links two nouns — 我是学生, 这是我的书. It is ONLY for noun = noun. It is NOT used before adjectives (你很高, never 你是高), NOT for location (在, not 是), and NOT for possession (有). English 'be' fans out into several Chinese patterns; 是 is just one of them.
- Adjectives Are Stative Verbs (No 是)HSK 1 — A Chinese adjective is a kind of verb — it predicates on its own, with NO copula 是 (shì). 她很高 'she is tall', 天气很好 'the weather is good', 这个太贵了 'this is too expensive' — never *她是高. 高 already means 'to be tall', so 是 has no job; negate with 不 (不高), not 没.
- The Default 很 (Linking hěn)HSK 1 — A plain predicate adjective normally takes an unstressed 很 (hěn) that does NOT mean 'very' — it is a neutral linker that makes the description sound complete: 我很好 'I'm fine', 他很高 'he's tall'.
- 是…的 for Known Past Events (Preview)HSK 2 — The 是…的 (shì…de) frame highlights one circumstance — the time, place, manner, or doer — of an already-known past event: 我是昨天来的 (it was yesterday that I came), 我是坐飞机来的 (it was by plane that I came). It is a cleft, not a past tense, and it pairs with 是, not 了.