We can meet on .
A:January 13th,2014
B:2014 January 13th
C:13th January 2014
某硝酸铵肥料中,含氮元素31.5%,已知其中的杂质不含氮,则该肥料中硝酸铵的质量分数为( )
2.4×2.4÷2.4×2.4=1
请解答下列问题: