alert
alert(警觉的,主动准备应对危险,形容当下状态)
vigilant
vigilant(警惕的,强调持续、不松懈地保持警觉,书面正式)
Security staff must stay alert throughout their shift, as suspicious activity can occur at any time.
安保人员必须在整个班次中保持警觉,因为可疑活动随时可能发生。
Citizens are urged to remain vigilant and report any unattended packages to the authorities immediately.
市民被敦促保持警惕,并立即向当局报告任何无人看管的包裹。