是不是: …, right? (confirmation)
句类 / sentence types (疑问句)
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
Sentence + 是不是？ / Subject + 是不是 + Verb…？
是不是 is used to check an assumption: you think something is true and want confirmation, like "…, right?" or "isn't it?".
It can go before the verb (你是不是不舒服？= you're not feeling well, are you?), at the start or at the end (你明天有空，是不是？).
Unlike 吗 (neutral question), 是不是 shows you already have an idea of the answer.
Examples
你周六是不是有空？
Nǐ zhōuliù shì bu shì yǒu kòng?You're free on Saturday, aren't you?
是不是你的生日快到了？
Shì bu shì nǐ de shēngrì kuài dào le?Isn't your birthday coming up?
我们七点见，是不是？
Wǒmen qī diǎn jiàn, shì bu shì?We're meeting at seven, right?
你是不是累了？
Nǐ shì bu shì lèi le?Are you tired?
Common mistakes
✗ 你是不是有空吗？ → ✓ 你是不是有空？ (no 吗).
It works with adjectives too: ✓ 你是不是很忙？