Perhaps you should try some spelling variations:
present challenges » current challenges, assessment challenges
challenges 2 » challenges 1, challenges 3, challenges 5
wang liang » wang yang
3 present » _ present
zhong zhi » zhang zhi, hong ghi, zhong tai
yang xi » yang yi, yang jui
2 zhong » 2 hong, ji zhong, wu zhong
png a » png _, lng a, peg 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 liang) or (((yang di) or (yang xi))))png a 3 present challenges 2 zhong zhi ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((wang liang) OR (((yang di) OR (yang xi))))png a 3 present challenges 2 zhong zhi ;.
• Adding a wildcard symbol may retrieve word variants: ((wang liang) or (((yang di) or (yang xi))))png a 3 present challenges 2 zhong zhi ;*.