Perhaps you should try some spelling variations:
present challenges » current challenges, assessment challenges
challenges xia » challenges 1, challenges 3, challenges 5
3 present » _ present
xia dang » xia fang, xia shang, xiao yang
yang xi » yang di, yang jui
yang yi » yang di, yang jui
png a » png _, lng a, peg a
lp a » lpg a, nlp a, up a
wang » wing, wan, lang
hai » hadi, haji, hari

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((wang yan) or (((yang xi) or (yang yi))))((png a) or (lp a)) 3 present challenges xia dang hai ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((wang yan) OR (((yang xi) OR (yang yi))))((png a) OR (lp a)) 3 present challenges xia dang hai ;.
• Adding a wildcard symbol may retrieve word variants: ((wang yan) or (((yang xi) or (yang yi))))((png a) or (lp a)) 3 present challenges xia dang hai ;*.