Perhaps you should try some spelling variations:
training visit » training crisis, training asia, training vet
trading case » trading costs, trade case
dual credit » rural credit, deals credit, equal credit
dong yang » dong hoang, wang yang, yang yang
yang yi » yang di, yang xi, yang jui
yi dual » via dual

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

• Performing a fuzzy search may retrieve terms with similar spellings: dong yang yi dual credit ((trading case) or (training visit)) cong shu ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: dong yang yi dual credit ((trading case) OR (training visit)) cong shu ;.
• Adding a wildcard symbol may retrieve word variants: dong yang yi dual credit ((trading case) or (training visit)) cong shu ;*.