国际储备的资产必须可以自由地与其他金融资产相交换，体现了国际储备的（）特点。

A.官方持有性

B.自由兑换性

C.充分流动性

D.普遍接受性

---Why hasn’t Jane arrived yet?  

---She ______ again in the morning.

A．shouldn’t have overslept

B．may have turned off the alarm clock

C．must have no one to call her

D．should have someone to wake her up