是不是
Written shì bù shì, said shì bú shì — 不 becomes bú before a fourth tone.
Meaning
- is or is not (used to form yes-no questions)
Example sentence
他是不是医生?
Is he a doctor?
Characters in 是不是
是 to be plus 不 not plus 是 — the affirmative-negative question. Chinese forms yes-no questions this way as often as with 吗.