断断

duàn duàn bù xíng

断断不行。

That will never do.

duàn duàn bù kě yǔn xǔ

断断不可允许

be absolutely forbidden

wǒ men duàn duàn bù néng zǒu huí tóu lù le

我们断断不能走回头路了。

We must never go back to the old ways.

duàn duàn zuò bù dé

断断做不得

That simply won't do.