do you know how long the China's government processing JW202? then, i need 'F', but my school told me that i cannot make 'F' visa, why?

The processing time of China's Government Jw202 is about 2 weeks, but the time varies. You have to wait for it. There is no other option. For less than 6 months study in China, you should apply for F visa, for more than 6 months study, you should apply for X visa.