Perhaps you should try some spelling variations:
ratings risk » patients risk
liang yang » wang yang, yang yang, huang yang
liang ying » liang liying, huang ying, zhang ying
risk along » risk among, ask along
along who » along two, wrong who
can cost » can costa, can post, chain cost
can lost » can lose, can post, 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 ((liang yang) OR (liang ying)) ((can cost) OR (can lost)) ratings risk along who ;~.
• Adding a wildcard symbol may retrieve word variants: wang ((liang yang) or (liang ying)) ((can cost) or (can lost)) ratings risk along who ;*.