switch closure

例句：

1. 1. The circuit was switched off before the power went out.
   在电力中断之前，电路被关闭了。
2. 2. The light switch was closed when we entered the room.
   我们进入房间时，灯的开关是关闭的。
3. 3.The engineer switched on the lights to make sure everything was working properly.
   工程师打开灯光以确保一切正常工作。