单项选择题
A.速度差 B.压力差 C.质量差 D.浓度差
A.1.05~1.1 B.1.1~1.15 C.1.15~1.2 D.1.2~1.25
A.1.1~1.2 B.1.2~1.3 C.1.3~1.4 D.1.4~1.5