“放哨”常见的英文表达有 “stand guard” 或 “keep watch”。
stand guard：侧重于表示在某个位置执行警戒、守卫的任务，强调处于站岗状态。例如：The soldiers stood guard at the entrance of the camp.（士兵们在营地入口处放哨。）
keep watch：更强调保持警惕、留意周围情况以防范危险，适用场景较广。例如：We took turns to keep watch during the night.（夜里我们轮流放哨。 ）