Perhaps you should try some spelling variations:
training visit » training crisis, training asia, training vet
trading case » trading costs, trade case
dong hoang » hong hong
hua credit » dual credit, a credit, du credit
hoang yi » hoang vu, yang yi, hoang sy
yi hua » li hua, ya hua, yi hui

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

• Performing a fuzzy search may retrieve terms with similar spellings: dong hoang yi hua credit ((trading case) or (training visit)) (cong OR congo) shu ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: dong hoang yi hua credit ((trading case) OR (training visit)) (cong OR congo) shu ;.
• The words AND, OR and NOT may confuse the search; try adding quotes: "dong hoang yi hua credit ((trading case) or (training visit)) (cong OR congo) shu ;".
• Adding a wildcard symbol may retrieve word variants: dong hoang yi hua credit ((trading case) or (training visit)) (cong OR congo) shu ;*.