Perhaps you should try some spelling variations:
cach hoc » cach thuc, cach thoi, dich hoc
hanh dai » hanh tai, hanh dao, vanh dai
lang xa » lang ha, dang xay, lang van
cac hoc » cac hop, bac hoc, cac toc
va hanh » van hanh, va thanh, va danh
te sac » te sach, te cac, te san
sac ky » cac ky, sai ky
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 ky ((nang x) or (lang xa)) hoi. hieu qua ((cac hoc) or (cach hoc)) va hanh dai cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sac ky ((nang x) OR (lang xa)) hoi. hieu qua ((cac hoc) OR (cach hoc)) va hanh dai cua tu.
• Adding a wildcard symbol may retrieve word variants: te sac ky ((nang x) or (lang xa)) hoi. hieu qua ((cac hoc) or (cach hoc)) va hanh dai cua tu*.