题目

—It's only seven p.m. I wonder _____________.—Maybe she had something important to do. A . why she left so early B . why did she leave so early C . why does she leave so early D . why she leaves so early 答案：A二次函数y=ax2+bx+c的图象如图所示，则一次函数y=bx+b2-4ac与反比例函数y=在同一坐标系内的图象大致为（ ）A．B．C．D．