Perhaps you should try some spelling variations:
present challenges » current challenges, assessment challenges
challenges ji » challenges 1, challenges 3, challenges 5
wang yang » wang yan, wang liang, wang yanling
a present » _ present, 3 present, 2 present
zhong tai » hong tan, hong hai, zhong zhi
ji zhong » 2 zhong, wu zhong, yu zhong
yang xi » yang di, yang jui
yang yi » yang di, yang jui
png a » png _, lng a, peg a
ng a » lng a, ngo a, g a

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) or (yang yi))))((ng a) OR (png a)) a present challenges ji zhong tai ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((wang yang) OR (((yang xi) OR (yang yi))))((ng a) OR (png a)) a present challenges ji zhong tai ;.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((wang yang) or (((yang xi) or (yang yi))))((ng a) OR (png a)) a present challenges ji zhong tai ;".
• Adding a wildcard symbol may retrieve word variants: ((wang yang) or (((yang xi) or (yang yi))))((ng a) OR (png a)) a present challenges ji zhong tai ;*.