当bǜ遇到第四声的音节，需要变成第二声
举例 bǘ yào bǘ shì
不 (bù) is 4th tone except when followed by another 4th tone, when it becomes second tone. E.g. (bù duì -----bú duì) 不对
bù yào-------- b ǘ yào 不要
bù shì--------bǘ shì. 不是
thank you !I was too careless
Reading aloud a text including 不 (bù) without any rehearsal is difficult for me. I sometimes make a mistake.
You need more practice
This is also our the difficulty in the teaching