Perhaps you should try some spelling variations:
cach thoi » cac thoi, cach thuc, cach noi
cach hoc » cach thuc, dich hoc, cac hop
hanh tai » thanh tai, hang tai, han tai
dang xay » dang van, van xay
te sach » toc sach
tai cua » thai cua, tai cuc, tri cua
va hanh » van hanh, va thanh, va danh
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
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 sach ky ((nang xa) or (dang xay)) hoi. hieu va ((cach hoc) or (cach thoi)) va hanh tai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky ((nang xa) OR (dang xay)) hoi. hieu va ((cach hoc) OR (cach thoi)) va hanh tai cua te.
• Adding a wildcard symbol may retrieve word variants: te sach ky ((nang xa) or (dang xay)) hoi. hieu va ((cach hoc) or (cach thoi)) va hanh tai cua te*.