Perhaps you should try some spelling variations:
hoc viet » hoc hien
cam thu » nam thu, cac thu, ca thu
cao hoi » cau hoi, co hoi, cao hoc
hieu ve » hieu van
hieu va » lieu va, hieu qua
van anh » van thanh, tuan anh, van minh
vi hoc » li hoc, va hoc
anh vi » hanh vi, anh va, anh ve
su sac » su sach, su cac, su xac
sac ky » cac ky, sai ky
cam tu » nam tu, dam tu, tam tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sac ky nang cao hoi. ((hieu ve) or (hieu va)) ((cam tu) OR (cam thu)) van anh vi hoc viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sac ky nang cao hoi. ((hieu ve) OR (hieu va)) ((cam tu) OR (cam thu)) van anh vi hoc viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sac ky nang cao hoi. ((hieu ve) or (hieu va)) ((cam tu) OR (cam thu)) van anh vi hoc viet".
• Adding a wildcard symbol may retrieve word variants: su sac ky nang cao hoi. ((hieu ve) or (hieu va)) ((cam tu) OR (cam thu)) van anh vi hoc viet*.