A.0.51 B.0.56 C.0.63 D.0.68
A.0.200~0.280 B.0.225~0.315 C.0.250~0.340 D.以上都不對(duì)
A.A=(0.25~0.3)d B.A=(0.35~0.4)d C.A=(0.45~0.5)d D.以上都不對(duì)