单项选择题
A.0.1 B.0.2 C.0.3 D.0.4
A.2.5 B.3.5 C.4.5 D.5
A.0.3 B.0.286+0.714(PNm/ΣPN) C.0.6 D.0.4+0.6(PNm/ΣPN)