The width of the vertical scroll bar and the height of the horizontal scroll bar are constant for a particular video driver and display resolution.
垂直滚动条的宽度和水平滚动条的高度对于特殊的视频驱动程序和显示分辨率来说是常量。
2
Generally, the crane driver depend on the experience and sight to set the height of the hook, which have some disadvantages of low precision and waste the human resource.
The hot-air balloon doesn't depend on power, but float by means of wind. Because the wind direction and speed vary with the height, the driver can choose the proper height as the flight required.