Perhaps you should try some spelling variations:
ratings risk » patients risk
strong why » strong wto, strong where
user cost » user costs
debt cost » debt cash
wrong why » wrong way, wrong who, wrong ways
yan yang » yang yang, yao yang, dan yang
wang » wing, wan, lang

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 yan yang ((user cost) OR (debt cost)) ratings risk ((wrong why) OR (strong why)) ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "wang yan yang ((user cost) or (debt cost)) ratings risk ((wrong why) OR (strong why)) ;~".
• Adding a wildcard symbol may retrieve word variants: wang yan yang ((user cost) or (debt cost)) ratings risk ((wrong why) OR (strong why)) ;*.