And if you want to have the cross-platform capabilities but do not want to draw at a low level, there are some other convenience drawing libraries that sit on top of Cairo.
如果需要跨平台功能，但是不需要低层绘图控制，那么可以使用在cairo之上构建的一些绘图库。
2
Radial loading is the amount of weight placed vertically above the axle. Sitting on a trike places an axial load on the bearings. The drawing below is a cross-sectional view of a radial bearing.