double six双六doubleadj.双重的；成双的；两倍的v.翻一番；使 ... 加倍n.两倍；双份double-cross seed双杂交种子double-floor type双层式double dissociation双重分离双重分离double coiled relay双线圈继电器double-roll press双辊压力机double-unit motor双电动机机组double fired boiler双燃烧管锅炉double-cage rotor双笼转子double Macarthy gin复式麦卡赛轧棉机double power supply双电源