题目

已知函数的定义域及值域均为，其图象如图所示，则方程根的个数为                   （    ）       A．2                            B．3                            C．5                           D．6 答案：DI know a little bit about Italy as my wife and I ________ there several years ago.    A. are going     B. had been    C. went          D. have been