2 sentences

1. 部队正在进行攻坚演习。

   bù​duì zhèng​zài jìn​xíng gōng​jiān yǎn​xí.

   The troops are conducting an assault exercise.

   Source: Dong Chinese Dictionary

2. 我们必须在核心技术上攻坚。

   wǒ​men bì​xū zài hé​xīn jì​shù shàng gōng​jiān.

   We must tackle the challenges of core technologies.

   Source: Dong Chinese Dictionary