利润函数为L（x）=（p－a）x－b，收益函数为R（x）=px，则成本函数为（）。
A.b－px
B.px+b
C.（a－p）x
D.b+ax
参考答案：D
如果2X=3Y，那么X：Y=______：______．
—Could you tell me ________________?
—I don’t know. It seemed to be cool, powerful and confident.
A．why “Carrier Style” is known to all in China
B．when was “Carrier Style” so popular in China
C．where “Carrier Style” is popular
D．how was “Carrier Style” well-known in China
