饮用水消毒常用的化学药剂是（）。
A.臭氧
B.高锰酸钾
C.氯仿
D.碘类消毒剂
E.氯类消毒剂
参考答案：E
The state of Michigan now requires sports fans to make an annual ______ of $125 to $500 a seat to keep their end zone perches at Michigan Stadium.
A．tributary
B．attribution
C．contribution
D．distribution
