短語詞組短語backing g pump 前級泵;預(yù)抽真空泵backing vacuum pump 前級真空泵high -backing pressure pump 高背后壓力泵forepump backing pump 預(yù)抽泵vacuum backing pump 真空旋轉(zhuǎn)泵backing pump forepump 預(yù)抽泵mechanical backing pump 前級機械泵backing pump for molecular pump 分子泵的前級泵 返回 backing pump