Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
va hanh » van hanh, va thanh, va danh
nang xa » nang x, nang ma, mang xa
cua tre » cua te, cuu tre, dua tren
lang xa » lang ha, dang xay, lang van
hieu ve » hieu va, hieu van
hanh di » hanh vi, hanh de, hang di
cac lop » cac hop, cac loai
te sac » te sach, te cac, te san
lop va » lap va, hop va, nop va
sac ky » cac ky, sai ky
ve cac » va cac, vien cac

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 (lang xa)) hoi. hieu ve cac lop va hanh di ((cua tre) OR (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sac ky ((nang xa) OR (lang xa)) hoi. hieu ve cac lop va hanh di ((cua tre) OR (cua triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sac ky ((nang xa) or (lang xa)) hoi. hieu ve cac lop va hanh di ((cua tre) OR (cua triet))".
• Adding a wildcard symbol may retrieve word variants: te sac ky ((nang xa) or (lang xa)) hoi. hieu ve cac lop va hanh di ((cua tre) OR (cua triet))*.