Perhaps you should try some spelling variations:
hoat hieu » dat hieu, hoa hien, hoi hieu
giang dan » gian dan, giang day, giang van
hieu suat » hieu luat, hieu qua
dung dat » dung va, dung tai
huu hieu » huu hiep, thuc hieu, thau hieu
dan hoat » van hoa, dan hoc, danh hoa
dat huu » dao huu, dai huu, dat hua
hieu va » lieu va, hieu qua
tin » tinh

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tin dung dat huu hieu va ) or ( manh giang dan hoat hieu suat ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tin dung dat huu hieu va ) OR ( manh giang dan hoat hieu suat ))*.