dualsn.双排气管系统dualadj.双重的；成双的n.双数dual-tandem双串式dual-period双周期Dual baseline双基线dual porosity双重介质dual teachers队伍建设dual antinomy二元对立dual emulsion二元乳化液dual IP stack双栈dual injector双喷孔喷嘴dual disposal混合处理, 混合排放