Perhaps you should try some spelling variations:
training volumes » trading volumes, trading volume, training vouchers
credit training » credit trading, credit rationing, credit rating
volumes cong » volume one, volumes book
dual credit » rural credit, deals credit, equal credit
yang yang » wang yan
wang yang » wang yan, wang liang, wang yanling
a dual » _ dual
dong » doing, long, done

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 sin) OR (((yang yang) OR (wang yang)))) a dual credit training volumes cong shu ;~.
• Adding a wildcard symbol may retrieve word variants: ((dong sin) or (((yang yang) or (wang yang)))) a dual credit training volumes cong shu ;*.