Introduction - If you have any usage issues, please Google them yourself
Zhang Yi-fei paper learn about the things people in the process of the beginning of all things just to see the phenomenon. This is the stage of perceptual awareness. At this stage also can not make any logical conclusion. With in-depth study of these feelings and impressions repeated a number of things, so in people' s minds an awareness of Health and from the mutation process which finally led to a logical conclusion. This is the stage of rational knowledge.