Perhaps you should try some spelling variations:
yang system » rating system, making system, buying system
zhang ping » zhang ming, zhang jing, zhang ting
ping wang » ping pong, hong wang
yang jun » yang jui, pang jun, yang jin
wai yan » wang yan, wei yang
yang xi » yang jui
yang yi » yang jui

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "((wai yan) OR (((yang xi) OR (yang yi)))) zhang ping wang ((yang jun) OR (yang di)) yang system ;~".
• Adding a wildcard symbol may retrieve word variants: ((wai yan) OR (((yang xi) OR (yang yi)))) zhang ping wang ((yang jun) OR (yang di)) yang system ;*.