Perhaps you should try some spelling variations:
present challenges » current challenges, assessment challenges
challenges min » challenges m, challenges making, challenges moving
wang yang » wang yan, wang liang, wang yanling
min hong » amin hong, tin hong, min hyoung
hong hai » shang hai, zhong tai, dang hai
4a 2 » a 2, 4 2, 4a 1
ca 2 » a 2, c 2, ch 2

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 di))ng ((4a 2) or (ca 2)) present challenges min hong hai ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((wang yang) OR (yang di))ng ((4a 2) OR (ca 2)) present challenges min hong hai ;.
• Adding a wildcard symbol may retrieve word variants: ((wang yang) or (yang di))ng ((4a 2) or (ca 2)) present challenges min hong hai ;*.