词汇	backward curve
释义	backward curve 反向曲线
随便看	underground drilling underground drilling unit underground drill rig underground drinking water resource underground drinking water source area underground drip irrigation underground drive underground driveway underground duct underground duct system underground dump truck underground dump trucks underground dustbin underground dwelling underground ear park underground earth buried antenna underground ecology under ground economic underground economic activity underground economies underground economy under ground economy UNDERGROUND ECONOMY IN INDIA undergrounded underground electric borer