题目

—Do you know how to improve my English? I don’t want to let my parents down.          —Well, I think you need to read more and practice more.        A. make … happy     B. make … excited  C. make… disappointed 答案：C已知点P是抛物线y2=4x上的动点，点P在y轴上的射影是M，点A的坐标是（4，a），则当|a|＞4时，|PA|+|PM|的最小值是______．