短语词组短语Flat fell seam attachment 平缝装置flat coal seam 水平煤层flat -seam 平缝flat lock seam joint 平面锁缝接头flat fillet seam 平角焊缝flat fell seam 保险缝;明包缝;平拼逢flat lock seam 槽缝flat butted seam 对头接缝;对接缝;对头接缝英语;翻译flat felled seam 明包缝 返回 flat seam