Perhaps you should try some spelling variations:
present challenges » current challenges, assessment challenges
recent challenges » recent changes, treatment challenges, emergent challenges
wang yang » wang yan, wang liang, wang yanling
hong ghi » zhong zhi, hong g, hong hai
sea la » sea lane, sea land, sea loan
la a » law a, lab a, la ia

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

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