—I agree with you. It's rude _______us to do that.
A:at, of
B:to, for
C:at, for
若a满足不等式组2a-1≤11-a2>2,则关于x的方程(a﹣2)x2﹣(2a﹣1)x+a+12=0的根的情况是( )