flat envelope head bit平头钻
flat envelope hairspring平游丝
flat envelope gauze oxidizer平网氧化器
flat envelope footed平底脚的
flat envelope fibre扁平截面纤维
flat envelope fillister screw有槽扁头螺杆
flat envelope glass furnace平板玻璃窑炉
flat envelope fly虱虻
flat envelope frequency response平坦频率响应曲线