单项选择题
A.2s-3s,3°-6°B.2s-3s,4°-7°C.3s-5s,3°-6°D.3s-5s,4°-7°
A.0.5mmB.1mmC.1.5mmD.2mm
A.2,0.5-0.8B.2,0.6-0.9C.3,0.5-0.8D.3,0.6-0.9