A组:1,6,7,12,13,18,19,…
B组:2,5,8,11,14,17,20,…
C组:3,4,9,10,15,16,21,…
则
I didn't hear your call because I ______ to music at that time.
P为抛物线x2=﹣4y上一点,A(1,0),则点P到此抛物线的准线的距离与P到点A的距离之和的最小值为( )