I was tired out, so I stopped the car a short rest.
① 28+45+72
②1+3+5+7+9
③ 100-57-23
在棱长为1的正方体ABCD-A1B1C1D1中,则平面AB1C与平面A1C1D间的距离( )
现代城市功能分区的特点是( )