Perhaps you should try some spelling variations:
trading cost » trading costs, training cost, trading case
dual credit » rural credit, deals credit, equal credit
cost coping » post coping, port coping, cost computing
hua credit » a credit, du credit, ida credit
coping shu » cong shu
yang yang » wang yang, wang yan
yang yao » wang yan, yang yi, yang fan

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: yang yang yao ((hua credit) or (dual credit)) trading cost coping shu ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: yang yang yao ((hua credit) OR (dual credit)) trading cost coping shu ;*.