It varies from person to person. I am ready to meet the challenge and have a strong interest in related topics, so Cheng Mingming of Nankai University will be a good choice. After all, Cheng Mingming's research in related fields has certain influence and can provide students with rich academic resources and guidance. Want to choose a relatively relaxed learning environment, or have little interest in related topics, then Cheng Mingming's group of Nankai University is not the best choice. In this case, you can consider choosing a research group that is relatively suitable for your own needs. To sum up, the learning difficulty of Cheng Mingming's group in Nankai University is inconclusive, mainly depending on the individual's academic background, interest and willingness to challenge. When choosing, carefully weigh the pros and cons, fully communicate with the tutor and make the decision that suits you best.