电闸

例句：

1. 1. The electrician had to disconnect the main power switch before starting the new project.
   电工在开始新项目之前必须断开主电源开关。
2. 2. The old house needed a new electrical system, so we replaced the old switch with a modern one.
   这所老房子需要一个新的电气系统，所以我们用一个现代的开关替换了旧的。
3. 3. When the lights flickered, the electrician quickly identified the problem and replaced the faulty switch.
   当灯闪烁时，电工迅速识别出了问题并更换了故障的开关。