题目

Mona told me to come to the party on time，but she herself didn't         .        A. grow up    B. show up   C. set out     D. go out 答案：B将一张画有直角坐标系的图纸折叠一次，使得点A(0，2)与点B(4，0)重合，若此时点C(7，3)与点D(m,n)重合，则m+n的值是_____________.