3 sentences

1. 部队已经部署在战斗前沿。

   bù​duì yǐ​jīng bù​shǔ zài zhàn​dòu qián​yán.

   The troops have been deployed at the front lines of the battle.

   Source: Dong Chinese Dictionary

2. 士兵们在阵地前沿构筑了坚固的防御工事。

   shì​bīng men zài zhèn​dì qián​yán gòu​zhù le jiān​gù de fáng​yù gōng​shì.

   The soldiers built strong fortifications at the front of their positions.

   Source: Dong Chinese Dictionary

3. 该大学在量子物理研究方面处于世界前沿。

   gāi dà​xué zài liàng​zǐ wù​lǐ yán​jiū fāng​miàn chǔ​yú shì​jiè qián​yán.

   The university is at the world's forefront of quantum physics research.

   Source: Dong Chinese Dictionary