Perhaps you should try some spelling variations:
present challenges » current challenges, assessment challenges
challenges ji » challenges 1, challenges 3, challenges 5
wang liang » wang yang
3 present » _ present
zhong zhi » zhang zhi, hong ghi, zhong tai
ji zhong » 2 zhong, wu zhong, yu zhong
yang xi » yang yi, yang jui
png a » png _, lng a, peg a

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 liang) OR (((yang di) OR (yang xi))))png a 3 present challenges ji zhong zhi ;~.
• Adding a wildcard symbol may retrieve word variants: ((wang liang) or (((yang di) or (yang xi))))png a 3 present challenges ji zhong zhi ;*.