短语词组短語Pull Back Power ring 倒後擦發條BACK UP RING KIT 備份環套件;備份圓環套件back support ring 後支承環Back up ring 支承環back sealing ring 後密封環back moving ring 廻位彈簧back locating ring 後定位環back contact ring 靜接點彈簧 返回 back ring