The perpendicular distance from the base of a geometric figure to the opposite vertex, parallel side, or parallelsurface.
平行面(底面)且侧面都是平行四边形的多面体。
2
If the glass were kept hot enough, it would flow over the molten tin until the top surface was also flat, horizontal and perfectly parallel to the bottom surface.
如果玻璃保持足够的温度,它就会在熔化的锡中流动,直到顶部表面也变得平整、水平,与底部表面完全平行。
3
If the universe's space-time is positively curved, like the surface of a sphere, parallel beams would come together.