Perhaps you should try some spelling variations:
ha nghiem » khao nghiem, thi nghiem, thu nghiem
dang nghe » lang nghe, nang nghe, cong nghe
nghiem so » nghiem son, nghiep so, nghiem do
dao nghe » day nghe, da nghe, nao nghe
dat nghe » day nghe, da nghe, van nghe
hoach ha » hoach va, hoach xay, hoach hoi
tu sach » thu sach, su sach, te sach
so hoc » co hoc, mo hoc, so hoa
d hoc » du hoc, ad hoc, de 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) or (dat nghe))) or (dang nghe)) d hoc ) or ( thu hoach ha nghiem so hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach ((((dao nghe) OR (dat nghe))) OR (dang nghe)) d hoc ) OR ( thu hoach ha nghiem so hoc )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach ((((dao nghe) or (dat nghe))) or (dang nghe)) d hoc ) or ( thu hoach ha nghiem so hoc ))*.