trench on

例句：

1. 1.The soldiers dug deep trench to protect themselves from the enemy.
   士兵们挖深壕沟以保护自己免受敌人攻击。
2. 2.The engineers were busy constructing trench for the new road.
   工程师们忙于为新道路修建战壕。
3. 3.The trench was filled with water and mud, making it difficult for the soldiers to move forward.
   战壕里积水和泥浆，使得士兵们难以前进。