smoke detecting alarm system

例句：

1. 1.The smoke detector in the kitchen is always on.
   厨房里的烟雾探测器总是开着。
2. 2.The smoke detector will sound an alarm if there's a fire.
   如果有火灾，烟雾探测器会发出警报。
3. 3. The smoke detector is easy to install and can be used in any room.
   烟雾探测器安装简单，可以用于任何房间。