A:12 倍
B:2倍
C:24 倍
D:2 倍
—Could you tell ______it is from your home to your school?—It's about fifteen minutes’ ride.
若a﹣2=b+c,则a(a﹣b﹣c)+b(b+c﹣a)﹣c(a﹣b﹣c)的值为( )
已知⊙O的半径为10cm,如果一条直线和圆心O的距离为10cm,那么这条直线和这个圆的位置关系为 ____.