On July 5th, Dr. Li Heng and Dr. Geng Weizhi returned to our group to visit the teachers and students. Dr. Li and Dr. Geng were Ph.D. students supervised by Prof. Xi and Prof. Zhang. During the visit, they toured our lab guided by Prof. Zhang. Finally, we took a group photo and expressed our gratitude to Dr. Li and Dr. Geng for visiting our group!