单项选择题
A.Φ50F8/h7B.Φ50H6/p5C.Φ50H6/m5D.Φ50H6/r5
A.Φ50F8/h7B.Φ50F6/h5C.Φ50H6/m5D.Φ50H6/h5
A.20B.28C.25D.31.5