2. "Protruding inward" and "extending outward" describe the continuous state of hand movement, not the specific stroke state of words. However, they indirectly and naturally reflect the stroke state. For example, the upward sloping "horizontal" is the "stretch" pen, and turn left; On the other hand, lying flat "horizontally" means "pouting inward" with a pen and turning right. So is "thinking".
3. Starting from "pouting inside" and finally "expanding outside"; It started with "external expansion" and finally "pouted internally". Start with a left turn and end with a right turn; It starts with a right turn and ends with a left turn.