Perhaps you should try some spelling variations:
regarding cong » regarding covid, regarding cross, regarding old
aid regarding » i regarding, data regarding, back regarding
dong nan » dong yang, dong sin, dong cao
dong bin » dong sin, dong di, dann bin
hua chen » jui chen, a chen, hua ren
yu chen » yu cheng, yi chen, yulu chen

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((dong nan) or (dong bin)) ya ((hua chen) OR (yu chen)) aid regarding cong shu ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((dong nan) OR (dong bin)) ya ((hua chen) OR (yu chen)) aid regarding cong shu ;.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((dong nan) or (dong bin)) ya ((hua chen) OR (yu chen)) aid regarding cong shu ;".
• Adding a wildcard symbol may retrieve word variants: ((dong nan) or (dong bin)) ya ((hua chen) OR (yu chen)) aid regarding cong shu ;*.