sentinel

哨兵、卫兵、警卫

Two sentinels stood at the gate throughout the night.

两名哨兵整夜守在大门口。

守护者、看守者文学

Tall pines rose like silent sentinels along the ridge.

高大的松树像沉默的守护者，矗立在山脊上。

警示指标、预警讯号正式

Doctors treat the infection as a sentinel for wider outbreaks.

医师把这个感染视为大规模疫情的预警讯号。

守卫、警戒正式

Guards sentineled the palace entrance around the clock.

警卫全天候守卫著皇宫入口。