Perhaps you should try some spelling variations:
present challenges » current challenges, assessment challenges
challenges m » challenges 1, challenges 3, challenges 5
wang yang » wang yan, wang liang, wang yanling
hong hai » shang hai, zhong tai, dang hai
yang xi » yang di, yang jui
yang yi » yang di, yang jui
m hong » ma hong, _ hong, a hong
ya a » a a, y a, yu a
ye a » yet a, e a, me 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 ((ya a) OR (ye a)) present challenges m hong hai ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((wang yang) OR (((yang xi) OR (yang yi))))ng ((ya a) OR (ye a)) present challenges m hong hai ;.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((wang yang) or (((yang xi) or (yang yi))))ng ((ya a) OR (ye a)) present challenges m hong hai ;".
• Adding a wildcard symbol may retrieve word variants: ((wang yang) or (((yang xi) or (yang yi))))ng ((ya a) OR (ye a)) present challenges m hong hai ;*.