Directly studying for a master's degree means finishing the master's course and directly transferring to a doctoral course without doing a master's thesis. This method can shorten the time of doctoral graduation. Doctor is a degree title, which means that a person has the ability or academic ability to produce original theoretical results. It is the highest degree at present (postdoctoral is not a degree). The extension material has a doctorate or equivalent academic ability, which means that a person has the ability to enter the academic stage from the learning stage. The ability to produce original theoretical results or academic ability is the core connotation of a doctoral degree, and it is also the most essential feature of a person with a doctoral degree. Doctor is a title for graduate students studying for a doctorate, and it can also be used to address people who have obtained a doctorate. Enrollment is mainly conducted through the "doctoral entrance examination" held by ordinary colleges and universities with doctoral programs and relevant scientific research institutions with doctoral training qualifications.