词汇	double convex ring
释义	double convex ring 双凸环
随便看	working offshore platform working of lodes working of metals working of mines working of paper working of patent working of plastics working of plastics bending-off machine working of plastics, by severing and welding working of RAIL working of RAILSin railway tracks working of RATTAN working of sheet metal working of state-forests working of stone working of veneer working of wood working of wood fibres, particles working of wood fibres, wood shavings working of wood gauging means working-oil working oil pressure working oil sump working oil temperature working on