Perhaps you should try some spelling variations:
ratings risk » patients risk
yan yang » yang yang, yao yang, dan yang
der cost » oder cost, user cost, debt cost
can cost » can costa, can lost, can post
can past » can east, can fast, can post
wan yan » wang yan, nan yan, wai yan
how shu » how shih, how slum
how she » how some, how safe, how shih

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

• Performing a fuzzy search may retrieve terms with similar spellings: wan yan yang ((((der cost) or (can cost))) or (can past)) ratings risk ((how shu) or (how she)) ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: wan yan yang ((((der cost) OR (can cost))) OR (can past)) ratings risk ((how shu) OR (how she)) ;.
• Adding a wildcard symbol may retrieve word variants: wan yan yang ((((der cost) or (can cost))) or (can past)) ratings risk ((how shu) or (how she)) ;*.