Perhaps you should try some spelling variations:
recent challenges » present challenges, recent changes, treatment challenges
challenges may » challenges m, challenges small, challenges moral
our recent » four recent
wang yang » wang yan, wang liang, wang yanling
may hong » can hong, ky hong, may hold
hong zhi » zhong zhi, hong ghi, zhang zhi
yang xi » yang di, yang yi, yang jui

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((wang yang) or (yang xi))ng ya our recent challenges may hong zhi ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((wang yang) OR (yang xi))ng ya our recent challenges may hong zhi ;.
• Adding a wildcard symbol may retrieve word variants: ((wang yang) or (yang xi))ng ya our recent challenges may hong zhi ;*.