Invited as an expert. Professor Feng Baisui has been engaged in clinical medical work in the First and Second Affiliated Hospitals of Zhengzhou University for nearly 30 years. He has diagnosed and treated tens of thousands of difficult and complicated digestive system diseases and accumulated rich clinical experience. As an expert, Director Feng Baisui was specially invited to the Department of Gastroenterology, the Second Affiliated Hospital of Zheng Da University. Therefore, 20-year-old Bai Feng was transferred from the First Affiliated Hospital to the Second Affiliated Hospital because he was specially appointed as an expert.