单项选择题
A.0.9,0.8B.0.8,0.9C.0.8,0.8D.0.9,0.9
A.0.7,0.7B.0.8,0.8C.0.7,0.8D.0.8,0.7
A.Cb20,2.0B.Cb20,1.5C.Cb25,2.0D.Cb25,1.5