Perhaps you should try some spelling variations:
among letters » among lecturers, among learners, among masters
range risk » change risk, manage risk, change risks
wang yang » wang yan, wang liang, wang yanling
yang yang » wang yan
can close » can lose, a close, can cause
yang can » yang fan, yang dean, yang jin

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 yang can close range risk ((among letters) OR (among teachers)) ;~.
• Adding a wildcard symbol may retrieve word variants: wang yang yang can close range risk ((among letters) or (among teachers)) ;*.