Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
toc sach » hoc sach, doc sach, thuoc sach
cac tuc » cac toc, cac tac, cac nuoc
hieu ve » hieu va, hieu van
nang co » nang cao, nang doc, nang noi
co hoi » co hoc, co loi
cac tu » cac thu, cach tu, cac du
xa dan » ca dan, xa dai, va dan
ca cau » cua cau, cac cau, can cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) ky nang co hoi. hieu ve ((cac tuc) or (cac tu)) xa dan ca cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky nang co hoi. hieu ve ((cac tuc) OR (cac tu)) xa dan ca cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ky nang co hoi. hieu ve ((cac tuc) or (cac tu)) xa dan ca cau tren".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ky nang co hoi. hieu ve ((cac tuc) or (cac tu)) xa dan ca cau tren*.