From the discussion of the methods of "invagination" and "outward expansion", it can be seen that when "invagination" occurs, food, middle finger and ring finger "press" the pen holder, pulling inward or turning right. At the same time, the thumb "holds" the pen and pushes it to the left, so the "extension" is completed at the same time. Using this method is two actions, two directions and one process. This is done at one time. In other words, "internal conflict" and "external expansion" cannot be completed separately.