Perhaps you should try some spelling variations:
challenges rates » challenges related, challenges patents, challenges risks
2 assessment » 3 assessment, 4 assessment, 1 assessment
rates among » deaths among
wang yang » wang yan, wang liang, wang yanling
among tai » among team, among a, among di
yang xi » yang di, yang yi, yang jui
ng a » lng a, ngo a, png 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 yang) or (yang xi))ng a 2 assessment challenges rates among tai ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((wang yang) OR (yang xi))ng a 2 assessment challenges rates among tai ;*.