A warning signal of danger or urgent problem

• The sound or message that alerts people

对危险或紧急情况的警报信号

• 提醒人注意的声音或信息

A device or system that detects danger and warns people

检测危险并发出警示的装置或系统

A timed alert set to sound, especially to wake someone

• An instance of such an alert sounding

定时发出的提示，尤指用于叫醒

• 该提示响起的一次

Sudden fear or anxiety about perceived danger

对感知到的危险的突然恐惧或不安

To make someone feel afraid or anxious

使某人害怕或不安

To warn or put on alert, especially of danger

警告或使警觉，尤指关于危险