Mine fire preventing and controlling always is the key question of coal industry safety in production.

矿井火灾的防治一直是煤炭工业安全生产的重点问题。

youdao

Mine fire preventing and controlling always is the key question of coal industry safety in production.

矿井火灾的防治一直是煤炭工业安全生产的重点问题。

youdao