Water inrush from the bottom coal layer in mining work faced now is rather serious in Northern China coalfield, which constraints seriously the normal economical benefits.

 
  • 在我国华北煤矿区,回采工作面煤层底板突水问题相当严重,困扰着煤矿经济效益的正常发挥。
今日热词
目录 附录 查词历史