Perhaps you should try some spelling variations:
learning costs » learning cost, cleaning costs, learning cross
costs among » costs along, customs among
wang liang » wang yang
liang yang » liang ying, wang yang, yang yang
among ers » among peers, among users, among east
can cost » can costa, can lost, chain cost
can post » can lost, can past, can postal

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 yang ((can cost) or (can post)) learning costs among ers ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: wang liang yang ((can cost) OR (can post)) learning costs among ers ;*.