sentinel

灯塔作为哨兵，在黑夜中指引船只避开危险。

The lighthouse serves as a ___sentinel, guiding ships away from danger in the darkness.

石狮作为哨兵守卫古庙大门两侧已有一千多年。

Stone lions have stood as ___sentinels flanking the ancient temple gate for over a thousand years.

一架无人机像电子哨兵一样在区域上空盘旋，将实时画面传回基地。

A lone drone circled the area like an electronic ___sentinel, feeding real-time footage back to base.