单项选择题
A.453.2g,452.9g B.425.9g,425.5g C.430.8g,430.1g D.442.3g,442.4g
A.1% B.0.2g C.0.5g D.0.5%
A.3,3 B.3,1 C.3,2 D.前三种方法均可