Perhaps you should try some spelling variations:
khach nhiem » trach nhiem
dat khach » dat khanh, vay khach, can khach
nghe duoc » nghiem duoc, nghe nuoi, che duoc
duoc hoc » quoc hoi
huu loc » hau loc, muu luoc
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
tu dat » tu bat

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu dat khach nhiem huu loc ) or ( ((tu sach) OR (su sach)) van nghe duoc hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu dat khach nhiem huu loc ) OR ( ((tu sach) OR (su sach)) van nghe duoc hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu dat khach nhiem huu loc ) or ( ((tu sach) OR (su sach)) van nghe duoc hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( tu dat khach nhiem huu loc ) or ( ((tu sach) OR (su sach)) van nghe duoc hoc ))*.