Perhaps you should try some spelling variations:
toc cach » toc sach, truoc cach, cuoc cach
hoc cach » hoc cac, hoc sach, cuoc cach
danh vai » danh sai, danh va, doanh van
vai cua » dai cua, hai cua, lai cua
va danh » va dinh, va dan, va hanh
cao suc » cao su, cao duc
cac suc » cac nuoc, cac cuoc, cac quoc
nano xa » nano va, nano bac, nano cau
tu nano » truc nano
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc cach) or (hoc cach)) tu nano xa hoi. hieu qua ((cac suc) OR (cao suc)) va danh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc cach) OR (hoc cach)) tu nano xa hoi. hieu qua ((cac suc) OR (cao suc)) va danh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc cach) or (hoc cach)) tu nano xa hoi. hieu qua ((cac suc) OR (cao suc)) va danh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((toc cach) or (hoc cach)) tu nano xa hoi. hieu qua ((cac suc) OR (cao suc)) va danh vai cua tre*.