Perhaps you should try some spelling variations:
ha nghiem » khao nghiem, thi nghiem, thu nghiem
sach dao » lanh dao
dao nghe » day nghe, da nghe, dat nghe
nghe det » nghe dien, nghe viet, nghe dan
hoach ha » hoach va, hoach xay, hoach hoi
tu sach » thu sach, su sach, te sach
det hoc » de hoc, den hoc, dien hoc
su hoa » su hoan, su hoat, su khoa
tu hoc » te 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 sach dao nghe det hoc ) or ( thu hoach ha nghiem ((su hoa) or (tu hoc)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach dao nghe det hoc ) OR ( thu hoach ha nghiem ((su hoa) OR (tu hoc)) )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach dao nghe det hoc ) or ( thu hoach ha nghiem ((su hoa) or (tu hoc)) ))*.