It's still a hole right now, but I will work hard to fill it in. Haha, my main focus is still on "Broken Wings". This article was actually written earlier than "Broken Wings". I used all the math classes in the second grade of junior high school to write this. There may be flaws in the content (intermittent, unable to connect from beginning to end), but I hope you experts can give me some advice. My little girl is very grateful!