trench edge

例句：

1. 1. The soldiers dug a trench to protect their position at the edge of the battlefield.
   士兵们挖了一条战壕以保护他们在战场边缘的位置。
2. 2.The ship's hull was marked with sharp edges that could cut through anything.
   船体的边缘锋利到能切割任何物体。
3. 3.The artist used a brush to create an edge that perfectly blended into the background.
   艺术家用刷子创造出一个完美融入背景的边缘。