The 是 Sentence: Saying A is B

One of the very first patterns you'll learn is how to say "A is B": 我是学生 (I'm a student). The word doing the work is 是 (shì), and it's the closest thing Chinese has to the English "is/am/are." It's simple, but there's one big trap that catches almost every beginner, so let's get it right from the start.

The basic pattern

The structure is exactly what you'd hope: A + 是 + B, where 是 links two nouns and says they're the same thing or that A belongs to category B.

• 我是学生。 (I'm a student.)
• 他是医生。 (He's a doctor.)
• 这是我的手机。 (This is my phone.)
• 北京是中国的首都。 (Beijing is China's capital.)

Both sides of 是 are nouns (or noun phrases). That's the key feature: 是 connects two nouns. A is B, where both A and B are things.

Making it negative

To say "A is not B," put 不 in front of 是:

• 我不是老师。 (I'm not a teacher.)
• 这不是我的。 (This isn't mine.)

Note it's always 不是, never 没是. The word 没 doesn't go with 是.

Asking the question

Two easy ways to turn it into a question.

Add 吗 at the end:

• 你是学生吗? (Are you a student?)

Or use the A-not-A pattern, 是不是:

• 你是不是学生? (Are you a student or not?)

Both get you a yes/no question. To answer, you can just say 是 (yes) or 不是 (no), which is handy.

The big trap: don't use 是 with adjectives

Here's the mistake nearly everyone makes. In English, "is" works with adjectives too: "She is happy," "The food is delicious." So learners naturally reach for 是 and say things like 她是高兴 or 这个菜是好吃.

This is wrong. In Chinese, you do not use 是 before an adjective. Adjectives act like verbs on their own, so they don't need a linking word. Instead you typically use 很 (hěn):

• 她很高兴。 (She's happy.) Not 她是高兴.
• 这个菜很好吃。 (This dish is delicious.) Not 这个菜是好吃.
• 今天很冷。 (It's cold today.) Not 今天是冷.

The rule of thumb: 是 connects two nouns. With an adjective, drop the 是 and use 很. Why 很 shows up here, and what it really means, is its own short article (adjective predicates), so we'll just flag it for now. The thing to lock in is: noun + 是 + noun, but subject + 很 + adjective.

When 是 can sit before an adjective-looking word

Just so you're not confused later: you'll occasionally see 是 before something that looks like an adjective, but in those cases it's adding emphasis or contrast, and the thing after it is really being treated like a fuller statement. For example, 这个菜是好吃 can be said to mean "This dish really is delicious (whatever you might think)." That's a special emphatic use, not the normal pattern, so set it aside until you're comfortable with the basics.

Quick recap

• A 是 B links two nouns: 我是学生.
• Negate with 不是: 我不是学生.
• Question with 吗 or 是不是.
• Never use 是 before a plain adjective. Use 很 instead: 她很高兴, not 她是高兴.

Get those four points down and you've got one of the most common sentence patterns in the language working correctly, trap and all.