Perhaps you should try some spelling variations:
cach hoc » cach thuc, cach thoi, dich hoc
van hanh » van thanh, ban hanh, van anh
hanh dai » hanh tai, hanh dao, vanh dai
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
cac hoc » cac hop, bac hoc, cac toc
te sac » te sach, te cac, te san
sac ky » cac ky, sai ky
cua te » cua tu

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 xa) or (van xay)) hoi. hieu va ((cac hoc) or (cach hoc)) van hanh dai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sac ky ((nang xa) OR (van xay)) hoi. hieu va ((cac hoc) OR (cach hoc)) van hanh dai cua te.
• Adding a wildcard symbol may retrieve word variants: te sac ky ((nang xa) or (van xay)) hoi. hieu va ((cac hoc) or (cach hoc)) van hanh dai cua te*.