不是...是...
Reach for 不是...是... when you want to swap one label for another on the fly — knock down the wrong one, plug in the right one. Spoken Chinese leans on this constantly: 'It's not tea, it's coffee,' 'It's not me who said that, it's him,' 'It's not about the money, it's about the time.' Both slots are usually nouns or noun-phrases. The 是 in the second half is mandatory — you can't drop it without making the sentence sound chopped.
Structure
[SUBJECT] 不是 [WRONG] ，是 [RIGHT]
bú shì... shì...
How to Think About It
Both halves are identification claims, so both need 是. The flow is correction: knock down, replace. Use the bare 是 version in speech and casual writing; switch to 不是...而是... when you want an argumentative, written-essay tone. The contrast lives entirely in the two nouns you slot in — if you're trying to negate an action instead of a label, you need a different pattern.
Examples
他不是我老板，是我同事。
Tā bú shì wǒ lǎobǎn, shì wǒ tóngshì.
He isn't my boss, he's my coworker.
今天不是周六，是周日。
Jīntiān bú shì zhōuliù, shì zhōurì.
Today isn't Saturday, it's Sunday.
问题不是钱，是时间。
Wèntí bú shì qián, shì shíjiān.
The problem isn't money, it's time.
Common Mistake
Learners forget the second 是 because English 'It's not tea, coffee' would feel okay in their head. Without the second 是 the sentence sounds like a fragment, and natives have to mentally fix it.
这不是茶，咖啡。
这不是茶，是咖啡。
Don't Confuse With
不是...而是...
Same correction logic, more argumentative register. Use 而是 in writing or when you're reframing an idea, not just swapping a noun.
不是...就是...
Means 'either A or B' — listing two possibilities, not correcting. The 就 changes the logic completely. '他不是日本人就是韩国人' = he's either Japanese or Korean.
并不是...
Adds 并 to firmly deny a strong assumption ('It's NOT actually X'). Often stands alone without a follow-up 是 clause: '我并不是不喜欢他.' Heavier negation than bare 不是.
Practice
这 ___ 我的，是他的。
Show answer
不是
她不是医生，___ 护士。
Show answer
是
Put in order: [不是 / 是 / 红色 / 这 / 蓝色]
Show answer
这不是红色，是蓝色。
Translate to Chinese: 'It's not my idea, it's his.'
Show answer
这不是我的主意，是他的。
Correct a wrong guess about something you ate or drank today, using 不是...是...
Show answer
Example answer: 我喝的不是咖啡，是奶茶。 (What I had wasn't coffee, it was milk tea.)
Hear It in Real Episodes
This pattern appears in 2 Fluentide episodes: