mine firing indicator

例句：

1. 1.Mine operators use this indicator to monitor the mine's safety conditions.
   矿用操作员使用这个指示器来监测矿井的安全状况。
2. 2. The mine fired an alarm when it detected a gas leak in the tunnel.
   当矿井检测到隧道中气体泄漏时，它发出了警报。
3. 3. The mine fired the indicator at the first sign of danger.
   矿井在第一次危险迹象出现时就启动了指示器。