2. Generate four viewports, as shown in the figure below.

3. Draw a rectangle in the first viewport, and you can see that four viewports have rectangles at the same time, which means that the four viewports are synchronous, and the same shape means that the four viewports have the same observation direction.

4. Select the first viewport, execute View-3D View-Main View, and then set the other three viewports in this order, such as looking down, looking left and isometric.

5. Draw a rectangle in the main viewport, draw a triangle connecting line in the isometric viewport, and draw a circle in the overlooking viewport. In each step, you can see that the four viewports change synchronously.