Perhaps you should try some spelling variations:
ratings risk » patients risk
paying users » parking users, drawing users, loading users
among ers » among peers, among users, among east
wang dan » wang yan, wang ban, wang yidan
dan yang » daun yang, tan yang, wang yang
can post » can cost, can past, can postal
can lost » can cost, can lose, can boost

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

• If you are trying to use Boolean operators, they must be ALL CAPS: wang dan yang ((can post) OR (can lost)) ratings risk ((among ers) OR (paying users)) ;~.
• Adding a wildcard symbol may retrieve word variants: wang dan yang ((can post) or (can lost)) ratings risk ((among ers) or (paying users)) ;*.