煤层顶底板
coal seam roof and floor
Roof and floor of coal seam
热带对流层顶层
tropical tropopause layer
深层板层切除
excision of deep lamellar
纸积层板托盘
multiply laminated paper pallet
大倾角地层煤层气钻井
CBM well boring in strata at great inclination
煤层煤质
coal seam a nd coal quality