白芥子具有的功效是
A．温肺祛痰，利气散结B．化痰止咳，和胃降逆C．消痰行水，降气止呕D．降气祛痰，宣散风热E．燥湿化痰，祛风止痉
参考答案：B
It's the first time that he has been to Australia, _____? [ ]
A. isn't he
B. hasn't he
C. isn't it
D. hasn't it
假如某永续年金每年都产生3000元的现金流，年利率为15%，那么它的现值是（）元。
A．5000
B．10000
C．20000
D．25000
