Perhaps you should try some spelling variations:
present challenges » current challenges, assessment challenges
challenges 5 » challenges 1, challenges 3
wang yang » wang yan, wang liang, wang yanling
zhong tai » hong tan, hong hai, zhong zhi
yang jui » yang judy, yang di, yang xi
yang yi » yang di, yang xi
5 zhong » 2 zhong, ji zhong, wu zhong

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 jui) or (yang yi))))ngo ((a a) OR (a la)) present challenges 5 zhong tai ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((wang yang) OR (((yang jui) OR (yang yi))))ngo ((a a) OR (a la)) present challenges 5 zhong tai ;.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((wang yang) or (((yang jui) or (yang yi))))ngo ((a a) OR (a la)) present challenges 5 zhong tai ;".
• Adding a wildcard symbol may retrieve word variants: ((wang yang) or (((yang jui) or (yang yi))))ngo ((a a) OR (a la)) present challenges 5 zhong tai ;*.