某市场销售的化肥硝铵，经检测知道其含氮量为34.3%，则该化肥含硝酸铵的质量分数为_________。（设其它成分不含氮元素）
98%
变压器的额定频率即是所设计的运行频率，我国为（）HZ。
A、45
B、50
C、55
D、60
—Would you mind my closing the window?
—______. [ ]
A. Certainly not
B. Yes, please
C. Sorry, won't
D. Yes, please not.
