When dealing with the water jet, when entering the BO shortcut key alone to close the polyline area, it reminds that the closed boundary cannot be determined, and the processing method with a small circle appears as follows:

1. Select the already processed lines of the graphic, enter the CO shortcut key to copy and move to the right

2. Delete the processed line segments on the left pattern and keep the unclosed line segments on the left.

3. Copy and move out the multiple line areas that cannot be closed separately, and then separate them into individual areas. Enter the BO shortcut key to close the polyline of the individual area.

4. After all the unclosed areas are moved out and closed separately, the patterns that have been processed individually with BO can be moved back to the graphic area processed in the first step, and then enter MY to generate the face domain.