Perhaps you should try some spelling variations:
training course » training courses
training risk » trading risk, training crisis, defining risk
dual credit » rural credit, deals credit, equal credit
dong sign » dong sin, among sign, dong bin
dong nan » dong yang, dong sin, dong bin
a dual » _ dual

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 sign)) a dual credit ((training risk) OR (training course)) cong shu ;~.
• Adding a wildcard symbol may retrieve word variants: ((dong nan) or (dong sign)) a dual credit ((training risk) or (training course)) cong shu ;*.