8"42 = 8.42英寸 = 8.42*25.4 = 213.868mm26 ' 11 = 26英尺11英寸 = (26*12 + 11)*25.4 = 8204.2mm = 8.2042m21 ' 9" = 21英尺9英寸 = (31*12 + 9)*25.4 = 9677.4mm = 9.6774m1英尺 = 12英寸1英寸 = 25.4mm
