2 sentences

1. 无论环境多么恶劣，他的志向依然很坚。

   wú​lùn huán​jìng duō​me è​liè, tā de zhì​xiàng yī​rán hěn jiān.

   No matter how harsh the environment, his ambition remains steadfast.

   Source: Dong Chinese Dictionary

2. 这种石头的质地很坚，普通的凿子凿不动。

   zhè zhǒng shí​tou de zhì​dì hěn jiān, pǔ​tōng de záo​zi záo bù dòng.

   This stone is very hard; an ordinary chisel can't make a dent in it.

   Source: Dong Chinese Dictionary