Theoretically, a doctoral supervisor can take doctors, masters and undergraduates; In fact, when teachers reach a certain age, they don't teach undergraduates first, then master's degree and finally doctor's degree.

Doctoral tutors can take a PhD or a master's degree. There is a problem in this way that people's energy is limited, and doctoral supervisors will focus on the distribution of teaching energy for doctors and masters. Old professors usually focus most of their energy on doctoral training, but it does not rule out that young doctoral supervisors will focus on master's training.