Perhaps you should try some spelling variations:
khach trai » khac trai, khanh tra
nghiep tai » nghiep va
nghe duoc » nghiem duoc, nghe nuoi, che duoc
kham trai » khac trai, pham tai, phai trai
khac thi » khau thi, khuc thi, khuat thi
thi nghe » thai nghe, thi nghiem, thi ngoc
duoc hoc » quoc hoi
vu khac » vu kham, vu khanh, bui khac
tai hoc » thai hoc, dai hoc, bai hoc

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: (( vu khac thi nghe duoc hoc ) OR ( cua ((kham trai) OR (khach trai)) nghiep tai hoc ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( vu khac thi nghe duoc hoc ) or ( cua ((kham trai) OR (khach trai)) nghiep tai hoc ))~".
• Adding a wildcard symbol may retrieve word variants: (( vu khac thi nghe duoc hoc ) or ( cua ((kham trai) OR (khach trai)) nghiep tai hoc ))*.