A:①②
B:①③
C:②④
D:③④
— Can you believe _________ little children can finish the difficult problem in _________ a short time?
— I can't believe it until I see it with my own eyes.
I want to know your age.
直线x-y+m=0与圆x2+y2-2x-1=0有两个不同交点,则m满足( ).