— Must we wear our school uniform this afternoon?

— No, you. All of us will go on an outing.

A．mustn't

B．can't

C．needn't

D．couldn't

（）是用以衡量资金时间价值的重要参数，代表资金占用所应获得的最低动态收益率，并且用作不同年份之间资金价值换算的折现率。

A．社会折现率

B．影子工资

C．国民经济增长率

D．影子汇率