When I first learned 不,the accompanying pinyin was given as

bù (falling tone).

But I've also been doing Pimsleur Chinese lessons and there is the example

wo bú hùi shuo ying wen

and here 不 is pronounced with a rising tone.

My question is:

Is there a rule to when it is bù and when bú? Or does it depend on the speaker's dialect?


2 Answers 2


The rule about sandhi of 不 is:

  1. It's pronounced in the original tone (the 4th tone) when being used alone or at the end.



  1. It's pronounced in the 2nd tone when being used before a 4th tone.


不对、不算、不便、不怕、不必、不屑  不怕、不当、不定、不动、不利、不顺

  1. It's pronounced in the 4th tone when being used before a tone other than the 4th tone.


不听、不悲、不分、不蒙、不穿、不飞 不同、不曾、不行、 不纯、不回、不白  不美、不想、不好、不许、不准、不满

  1. It's pronounced in the neutral tone when being used in the middle of words.




becomes when it precedes a falling tone.

I don't know -> wǒ bù zhī dǎo

I don't do -> wǒ bú zuò

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