不 bù / bú
不 rises to bú before a fourth tone
Structure
不 + 4th → bú
What it means
不 (not) is normally bù, but before a fourth tone it changes to a rising bú.
How it is built
不 + 4th-tone syllable → bú: 不是 bú shì, 不对 bú duì. 我不是中国人 (I'm not Chinese). Before tones 1, 2 and 3 it stays bù: 不好 bù hǎo.
When to use it
Make the change every time you speak: 不客气 bú kèqi (You're welcome). In 对不起 (sorry) the 不 is light and quick: duìbuqǐ.
Watch out
Don't say two falling tones in a row: ✗ bù shì ✓ bú shì. And don't change 不 before other tones: 不好 stays bù hǎo.
Examples
我不是中国人。
I’m not Chinese. (bú shì)
不对，他是王明。
No, he’s Wang Ming. (bú duì)
不客气！
You’re welcome! (bú kèqi)
我中文不好。
My Chinese isn’t good. (bù hǎo: no change)
Learn this in 启蒙 · Lesson 3: 对不起 (Tones that change)
A dialogue, a reading, word cards with audio and a drill that uses it, in Learn Chinese with Bao. This lesson is free.
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