You can contact in advance. If you are interested in the tutor, you can check whether the enrollment plan meets your own needs, and you can also understand the tutor's requirements and expectations for graduate students. If you are very interested in a certain research field, you can find famous tutors in this field and communicate with them to understand their research direction, research results and requirements for graduate students. The Department of Mathematics of South China University of Technology is one of the famous higher mathematics education and research institutions in China, and its mathematics major enjoys a high reputation both inside and outside the province.