定时锁

例句：

1. 1. The alarm clock has a timer feature that can be set for specific times.
   闹钟有定时功能，可以设置特定时间。
2. 2. She used the timer to keep track of how long she spent on her homework.
   她用定时器来记录自己做作业花了多长时间。
3. 3. The security system has a timer that activates when someone enters the building.
   安全系统有一个定时器，当有人进入大楼时会启动。