3 sentences

1. 矿工们正在加固矿井里的木头支柱。

   kuàng​gōng men zhèng​zài jiā​gù kuàng​jǐng lǐ de mù​tou zhī​zhù.

   The miners are reinforcing the wooden pillars inside the mine.

   Source: Dong Chinese Dictionary

2. 这座矿井因安全隐患而被暂时关闭。

   zhè zuò kuàng​jǐng yīn ān​quán yǐn​huàn ér bèi zàn​shí guān​bì.

   The mine shaft was temporarily closed due to safety hazards.

   Source: Dong Chinese Dictionary

3. 矿井中必须安装防跑车装置以确保工人的安全。

   kuàng​jǐng zhōng bì​xū ān​zhuāng fáng pǎo​chē zhuāng​zhì yǐ què​bǎo gōng​rén de ān​quán.

   Anti-runaway devices must be installed in mines to ensure worker safety.

   Source: Dong Chinese Dictionary