double fin双立尾doubleadj.双重的；成双的；两倍的v.翻一番；使 ... 加倍n.两倍；双份double-fed machine双馈电机Double text segments双文本段double-regenerator双蓄热double acting feeder双动进料器double length number双倍长数Double censored data左右删失double helical chain双螺旋链double shear coaxial同轴双剪切double-arming bolt无头穿钉double aperture slit双狭缝