Perhaps you should try some spelling variations:
training risk » trading risk, training visit, training work
training cost » training costs, training course, trading costs
dual credit » rural credit, equal credit, rural credits
dong nan » dong yang, dong bin, dong cao
ya dual » a dual
sin » skin, sign, sink
cong » congo, long, hong

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: ((dong nan) OR (dong sin)) ya dual credit ((training risk) OR (training cost)) cong shu ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((dong nan) OR (dong sin)) ya dual credit ((training risk) or (training cost)) cong shu ;~".
• Adding a wildcard symbol may retrieve word variants: ((dong nan) OR (dong sin)) ya dual credit ((training risk) or (training cost)) cong shu ;*.