dualsn.双排气管系统dualadj.双重的；成双的n.双数dual elevator双台电梯Dual gas flow双气流路dual solenoid双电磁阀dual-medium双重介质dual variable对偶变量dual-system[计] 双机系统dual-alkali双碱法脱硫工艺dualautomaticadj.双自动的dual strategy双策略Dual-thresh双阈值