一般洪水是指洪峰流量或洪量的重现期为（）年一遇的洪水
A.5～10
B.10～20
C.20～50
D.大于50
参考答案：A
已知某投资中心的资本周转率为0.9次，销售成本率为30%，成本费用利润率为 70%，则其投资利润率为( )。
A．18.9%
B．22.1%
C．12%
D．30.5%
______ for the free tickets, I would not have gone to see films so often.
A．If it is not
B．Had it not been
C．Were it not
D．If they were not
