Definition: pointing straight up from a surface Level: C1
在黑板上画一条垂直线。
Draw a ___vertical line on the board.
在图表上，纵轴代表时间。
On the graph, the ___vertical axis represents time.
登山者攀爬了近乎垂直的悬崖面。
The climber scaled the nearly ___vertical cliff face.
