题目

After inspecting the building，specialists discovered some faults that otherwise _______． A．had been overlooked                                B．would have been overlooked C．were overlooked                                        D．would be overlooked 答案：B设A={0，1，2，4}，B={12，0，1，2，6，8}，下列对应法则能构成A到B的映射的是（　　）A．f：x→x3-1B．f：x→（x-1）2C．f：x→2x-1D．f：x→2x