Go to college first, and then get a bachelor's degree after graduation. Then go on to study for a master's degree. What we usually call postgraduate entrance examination is to take a master's degree. Get a master's degree after graduation. After that, I studied as a doctoral student, which is what we usually call Kao Bo, and got my doctorate after graduation.

These are all obtained at the first level. Master and doctor refer to, while graduate students include master and doctor. It is clear to distinguish these.

As for postdoctoral, it refers to a stage in which doctoral students get their doctorate after graduation and then engage in similar research, which can be called postdoctoral.