卜商
Every PhD program with reputation has a residence requirement. Residence means you must attend the program on a full time basis. Normally, the residence requirement is about 2 years, ring which, you have to complete some foundation courses, usually in research methodology and some catch-up courses assessed by your professor. You also have to finish the thesis proposal and complete most of the lab work.After the residence, you can retire yourself to anywhere in the world, with your lab data and thesis proposal to start your writing work. You may travel to school about a few times a year to discuss your thesis with your professor. You can get a full time job as well.Most programs will have the maximum time limit, usually 8 to 10 years.In a nutshell, the minimum is 2 and the maximum is like 10. If you fail to obtain your PhD in the maximum time allowed, your option is to downgrade your degree to an MPhil to graate first.研究生2到3年,博士就难了,西部学校4年,但不受知名学校认可,东北部5到7年很难拿下,10年的大有人在,美国博士很难,不象国内这么水,在美国许多人一辈子写不出含金量高的论文,无法毕业