people in your family wear glasses? [ ]
A. How
B. How much
C. How many
答案：C
如图所示的实验操作正确的是[ ]
A.
B.
C.
D.
某企业年新鲜工业用水0.9万吨，无监测排水流量，排污系数取0.7，废水处理设施进口COD浓度为500mg/L，排放COD浓度为100mg/L。该企业去除 COD( )kg。
A．25200000 B．2520000C．2520 D．25200
