题目

— Food safety is very important.               — So some laws (法律) must    stop people from polluting food.        A. make         B. be made to         C. be made      D. make to 答案：B设函数f（x）=ax2+bx+c（a，b，c∈R），若x=-1为函数y=f（x）ex的一个极值点，则下列图象不可能为y=f（x）的图象是（ ）A．B．C．D．