triggered-time clock

例句：

1. 1.The alarm clock on the desk is set for 7:00 AM.
   桌子上的闹钟设定为早上7点。
2. 2.He used a timer to measure the reaction of the chemicals.
   他用计时器测量了化学物质的反应。
3. 3. The timer stopped at 10:30 PM, so we knew it was time to go home.
   计时器在晚上10点半停止，所以我们知道该回家了。