Perhaps you should try some spelling variations:
recent challenges » present challenges, recent changes, treatment challenges
aid recent » asia recent, a recent
zhong zhi » zhang zhi, zhong tai
hong ghi » hong g, hong hai
ngo dan » ngo van, ngo diana, ngo jean
dan aid » dan aids, can aid, dan asia
wang » wing, wan, lang
yang » lang

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((wang yanling) or (yang di))ngo dan aid recent challenges 1 ((hong ghi) or (zhong zhi)) ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((wang yanling) OR (yang di))ngo dan aid recent challenges 1 ((hong ghi) OR (zhong zhi)) ;.
• Adding a wildcard symbol may retrieve word variants: ((wang yanling) or (yang di))ngo dan aid recent challenges 1 ((hong ghi) or (zhong zhi)) ;*.