单项选择题
A.90°-120°B.120°-180°C.180°-270°D.270°-360°
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