2 sentences for 主力军 (zhǔ​lì​jūn — main force)

1. 这支主力军在关键时刻发起了进攻。

   zhè zhī zhǔ​lì​jūn zài guān​jiàn shí​kè fā​qǐ le jìn​gōng.

   This main force launched an offensive at the critical moment.

   Source: Dong Chinese Dictionary

2. 主力军在正面战场上击退了敌人的进攻。

   zhǔ​lì​jūn zài zhèng​miàn zhàn​chǎng shàng jī​tuì le dí​rén de jìn​gōng.

   The main forces repelled the enemy's attack on the front line.

   Source: Dong Chinese Dictionary