妈妈说今天不能吃冰淇淋，不行就是不行。

māma shuō jīntiān bù néng chī bīngqílín, bùxíng jiùshì bùxíng.

Mom said no ice cream today — no means no.

这个方案不行，我们得重新想一个。

zhège fāng'àn bùxíng, wǒmen děi chóngxīn xiǎng yí gè.

This plan won't work; we need to come up with a new one.

你不吃早饭可不行，对身体不好。

nǐ bù chī zǎofàn kě bùxíng, duì shēntǐ bù hǎo.

You can't skip breakfast — it's bad for your health.