How I can combine polygonal selection and outline selection at the same time

moved to Krita -> General Help

Hello tranquochuy,
Here are some useful informations on how to use selection modifiers:
https://userbase.kde.org/Krita/Manual/Tools/RectangleSelect

They are configured as follows:
Shift+click: add to selection.
Alt+click: subtract from selection.
Shift+alt+click: intersect selection
Ctrl+click: replace selection (for when you have set the selection mode to something else but replace).