bù xíng
开玩笑可以，欺负人可不行。
kāi wánxiào kěyǐ, qīfu rén kě bùxíng.
Joking is fine, but bullying people is not acceptable.
你知道，我在工程技术方面是不行的。
nǐ zhīdào, wǒ zài gōngchéng jìshù fāngmiàn shì bùxíng de.
You know, I'm not good at engineering and technology.
老太太病重，眼看不行了。
lǎotàitai bìngzhòng, yǎnkàn bùxíng le.
The old lady is seriously ill and doesn't look like she'll make it.