Some movements involving primarily vertical or horizontal motions of the body as a whole, in which rotations can be ignored, can be studied using simple equations of linear motion in three dimensions.
有些运动主要涉及整体的垂直或水平运动，其中转动可以忽略，可以用三维线性运动的简单方程来研究。
2
We define a header cell as a cell in the top or side headers, which we also call horizontal and verticaldimensions.
我们将标题单元格 定义为顶部或侧边的标题，也称为水平和竖直维度。
3
The horizontal and verticaldimensions are treated symmetrically.