Perhaps you should try some spelling variations:
recent challenges » present challenges, recent changes, treatment challenges
challenges may » challenges m, challenges small, challenges moral
four recent » our recent
wang yang » wang yan, wang liang, wang yanling
may hold » may hall, may help, why hold
yang xi » yang di, yang yi, yang jui
ya four » a four

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 yang) OR (yang xi))ng ya four recent challenges may hold zhi ;~.
• Adding a wildcard symbol may retrieve word variants: ((wang yang) or (yang xi))ng ya four recent challenges may hold zhi ;*.