How to master the human body structure quickly?

Still need to practice more. Buy a book about human body structure first and recommend a book to you. The book Deconstruction of Human Body: Artistic Human Anatomy recommended by the teacher is very good. You can buy it, copy it first, and present more masterpieces. Then I have to think more about why some people draw like this. Originally, sketches needed a lot of copying. Elbow grease gives the best polish. Come on, I wish you an early success! !