Perhaps you should try some spelling variations:
khach trai » khac trai, khanh tra
kham trai » khac trai, pham tai, phai trai
nghiem de » nghiem d, nghiem te, nghiem ve
tu cach » tu cac
cach tu » cach thuc
tu nghe » xu nghe, su nghe, te nghe
nghe va » nghe dan
va hoc » van hoc
de hoc » te hoc, du hoc, dien hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu cach tu nghe va hoc ) or ( te ((khach trai) OR (kham trai)) nghiem de hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu cach tu nghe va hoc ) OR ( te ((khach trai) OR (kham trai)) nghiem de hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu cach tu nghe va hoc ) or ( te ((khach trai) OR (kham trai)) nghiem de hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( tu cach tu nghe va hoc ) or ( te ((khach trai) OR (kham trai)) nghiem de hoc ))*.