Perhaps you should try some spelling variations:
trading cost » trading costs, training cost, trading case
cost coping » post coping, port coping, cost computing
hua credit » dual credit, a credit, du credit
coping shu » cong shu
yang yang » wang yang, wang yan
yang yala » yang yao, yang all, yang dali

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 yala ((hua credit) or (ida credits)) trading cost coping shu ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: yang yang yala ((hua credit) OR (ida credits)) trading cost coping shu ;*.