Perhaps you should try some spelling variations:
dan vanh » dan canh, dan hanh, dang hanh
vanh dai » van dai, vanh tai, lanh dao
te sach » toc sach
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
qua cac » cua cac
cac hoc » cach hoc, cac hop, bac hoc
te sac » te cac, te san
cua tu » cua tuc, cua su, cua cu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sac) or (te sach)) ky ((nang xa) or (lang xa)) hoi. hieu qua cac hoc dan vanh dai cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sac) OR (te sach)) ky ((nang xa) OR (lang xa)) hoi. hieu qua cac hoc dan vanh dai cua tu.
• Adding a wildcard symbol may retrieve word variants: ((te sac) or (te sach)) ky ((nang xa) or (lang xa)) hoi. hieu qua cac hoc dan vanh dai cua tu*.