短语词组短语Elbow rolling line 转弯滚筒线elbow seam line 小袖内撇线EL ELBOW LINE 手肘线line elbow 管路弯头air line elbow 气管弯头water line elbow 水管弯头fuel return line elbow 回油管弯头stright line of elbow 肘直线straight line of elbow 肘直线 返回 elbow line