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

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