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 lane highway双车道公路double-layer soil双层土壤double maximization双重最大化double vault tunnel双拱隧道double color effect双色效应double private bank双试线用触排double-pole relay双组触点式继电器,双极继电器double-cut planer双向切削龙门刨double backpressure双背压double sided waxing双面涂蜡