2 sentences for 坚韧 (jiān​rèn — tough)

1. 古代劳动人民常用坚韧的大麻纤维来织布。

   gǔ​dài láo​dòng rén​mín cháng​yòng jiān​rèn de dà​má xiān​wéi lái zhī​bù.

   Ancient laborers often used tough hemp fibers to weave cloth.

   Source: Dong Chinese Dictionary

2. 这种材料既轻便又坚韧，非常适合制作登山绳。

   zhè zhǒng cái​liào jì qīng​biàn yòu jiān​rèn, fēi​cháng shì​hé zhì​zuò dēng​shān​shéng.

   This material is both lightweight and tough, making it ideal for climbing ropes.

   Source: Dong Chinese Dictionary