单项选择题
A.正向拍卖 B.逆向拍卖 C.垂直拍卖 D.双边竞价拍卖
A.CNN.com B.ESPN.com C.MP3.com D.MSN.com
A.B2C(BusinesstoCustomer) B.B2B(BusinesstoBusiness) C.B2B2C(BusinesstoBusinesstoCustomer) D.B2B2B(BusinesstoBusinesstoBusiness)