上QQ阅读APP看书，第一时间看更新
Axis
These are number lines representing the scale of the graphs being plotted. Two-dimensional graphs have an x axis and a y axis, and three-dimensional graphs have an x axis, a y axis, and a z axis.
Don't get confused between axes and axis. Axis is an element of axes. Grammatically, axes is also the plural for axis, so interpret the meaning of axes depending on the context, whether multiple axis elements are being referred to or an axes object is being referred to.