A:dare to say; dare climbing
B:dare say; dares to clim
C:dare say; dares clim
D:dare to say;dares to climbing
已知平面α∥平面β,m⊂α,n⊂β,且直线m与n不平行.记平面α、β的距离为d1,直线m、n的距离为d2,则( )
已知等比数列{an}的第5项是二项式(x﹣13x)6展开式的常数项,则a3a7=____