Perhaps you should try some spelling variations:
khao nghiem » khao nghiep
ha nghiem » thi nghiem, thu nghiem, van nghiem
cac nam » bac nam, cac cam, cai nam
cac ham » cac cam, cac hat, cac nhan
nghe d » nghe di, nghe _, nghe 新
su hoc » tu hoc, du hoc, so hoc
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 ((cac nam) OR (cac ham)) nghe d hoc ) or ( thu hoach ((ha nghiem) or (khao nghiem)) su hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu ((cac nam) OR (cac ham)) nghe d hoc ) OR ( thu hoach ((ha nghiem) OR (khao nghiem)) su hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu ((cac nam) OR (cac ham)) nghe d hoc ) or ( thu hoach ((ha nghiem) or (khao nghiem)) su hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( tu ((cac nam) OR (cac ham)) nghe d hoc ) or ( thu hoach ((ha nghiem) or (khao nghiem)) su hoc ))*.