Thank you Xiaobaitu! Some more related questions.

Should I show them my I-20 and a financial statement of my assistantship from the University? I am still a student working as RA.

Actually, I have worked as RA after I filed my I-485 without EAD for a period of time. Will it cause any trouble?

Last question is whether using AP will affect my application for H-1 visa in the future.

Thanks again!!