Perhaps you should try some spelling variations:
doom using » from using
hua rents » hua ren
rents yan » ren yan
done sin » dong sin, done using, done so
long shu » cong shu, tong shui, long du
wong sau » wong sam, wong siu, wong shiu
yan jiu » yang jie, yang jin, pang jiu

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: ((done sin) OR (doom using)) ya hua rents yan jiu ((long shu) OR (wong sau)) ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((done sin) or (doom using)) ya hua rents yan jiu ((long shu) OR (wong sau)) ;~".
• Adding a wildcard symbol may retrieve word variants: ((done sin) or (doom using)) ya hua rents yan jiu ((long shu) OR (wong sau)) ;*.