单项选择题
A.(1:0.3)~(1:0.5) B.(1:0.2)~(1:0.5) C.(1:0.5)~(1:0.7) D.(1:0.2)~(1:0.7)
A.0.1 B.0.2 C.0.3 D.0.4
A.2 B.3 C.4 D.5