Perhaps you should try some spelling variations:
present challenges » current challenges, assessment challenges
challenges xia » challenges 1, challenges 3, challenges 5
3 present » _ present
lang yan » wang yan, wang yang, zhang yan
fang hai » dang hai, shang hai, eang hay
yang xi » yang di, yang jui
yang yi » yang di, yang jui
png a » png _, peg a
lng a » lng _, leg a, lpg a

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((lang yan) OR (((yang xi) OR (yang yi))))((png a) OR (lng a)) 3 present challenges xia fang hai ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((lang yan) OR (((yang xi) OR (yang yi))))((png a) OR (lng a)) 3 present challenges xia fang hai ;".
• Adding a wildcard symbol may retrieve word variants: ((lang yan) OR (((yang xi) OR (yang yi))))((png a) OR (lng a)) 3 present challenges xia fang hai ;*.