已知NH4NO3和KH2PO4固体混合物中氮元素的质量分数为28%,则混合物中KH2PO4的质量分数为 ( )
A:20%
B:25%
C:85%
D:80%
clean close clever class cloudy clothes
(I)B,C,D,E四点共圆;
(II)AB•AD=AC•AE.