单项选择题
A.10% B.年龄数% C.(12+年龄)% D.(12-年龄)% E.1/2
A.2.0ml B.3.0ml C.1.5ml D.0.5ml E.2.5ml
A.1/2 B.1/3 C.1/4 D.3/5 E.2/3