Perhaps you should try some spelling variations:
ratings risk » patients risk
user cost » user costs
yan yang » yang yang, yao yang, dan yang
can lost » can cost, can lose, can post
can past » can east, can fast, can post
wai yan » wang yan, wei yang
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: wai yan yang ((((user cost) or (can lost))) or (can past)) ratings risk ((how shu) or (how she)) ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: wai yan yang ((((user cost) OR (can lost))) OR (can past)) ratings risk ((how shu) OR (how she)) ;.
• Adding a wildcard symbol may retrieve word variants: wai yan yang ((((user cost) or (can lost))) or (can past)) ratings risk ((how shu) or (how she)) ;*.