题目

The teacher apologized ____ late.     A. to his students to arrive          B. to his students for arriving     C. for his students to arrive        D. for his students for arriving   答案：B二次函数y=ax2+bx+c的图象如图所示，则一次函数y=bx-ac与反比例函数在同一坐标系内的图象大致为（ ）A．B．C．D．