题目

He was a much older tennis playerbut he had the great _____ of experience. A.advantage       B. deal         C. value         D. number   答案：Ａ  若曲线f（x）=cosx与曲线g（x）=x2+bx+1在交点（0，m）处有公切线，则b=（　　）A．-1B．0C．1D．2