单项选择题
A.Φ6 B.Φ8 C.Φ10 D.Φ12
A.μN=0.81<0.95,满足三级要求 B.μN=0.81<0.85,满足二级要求 C.μN=0.80<0.85,满足二级要求 D.μN=0.80<0.95,满足三级要求
A.0.65 B.0.70 C.0.75 D.0.82