Hi, thanks on your reply.
You give a wise advice. As I have been working for quite a while, I do have some big names on mind whose work interests me. But my consideration is that: one, they may not be interested to take me; two, they may not be free to teach and guide for the graduate study. This said, I am not seeking a professor who teaches hands by hands, but at least be available to discuss when there is some difficulties.I think I should take your suggest, try to study some more faculties, who might be more available.
Good Luck for your application as well!