题目

— Did you pass the driving test?        —No．I ______ it, but I had little time practicing．        A．could have passed                           B．must have passed        C．can’t have passed                            D．shouldn’t have passed 答案：A已知函数f(x)=(m2+2m)·x,m为何值时，f(x)是 (1)幂函数； （2）正比例函数； （3）反比例函数； （4）二次函数.