2 sentences

1. 如果前提是错误的，那么推导出的结论也站不住脚。

   rú​guǒ qián​tí shì cuò​wù de, nà​me tuī​dǎo chū de jié​lùn yě zhàn​bu​zhù​jiǎo.

   If the premise is wrong, then the conclusion drawn will also be untenable.

   Source: Dong Chinese Dictionary

2. 数学老师在黑板上把这道题的推导过程演了一遍。

   shù​xué lǎo​shī zài hēi​bǎn shàng bǎ zhè dào tí de tuī​dǎo guò​chéng yǎn le yī biàn.

   The math teacher demonstrated the derivation of this problem on the blackboard.

   Source: Dong Chinese Dictionary