Perhaps you should try some spelling variations:
hieu ket » hieu kem, thien ket, lien ket
dua tren » dung tren
ban hanh » ban hang
lang van » dang van, tang van, hoang van
cuu tre » cua tre, cau tren, cau treo
hanh de » hanh ve, hanh kem
duc ban » duc tan, duc van, dua ban
cao duc » dao duc, cao suc, giao duc
ket cao » ket cau, kieu cao
lang xa » lang ha, dang xay
sai ky » sac ky
te sai » te tai, te bai, te lai

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sai ky ((lang xa) OR (lang van)) hoi. hieu ket cao duc ban hanh de ((dua tren) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sai ky ((lang xa) OR (lang van)) hoi. hieu ket cao duc ban hanh de ((dua tren) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sai ky ((lang xa) OR (lang van)) hoi. hieu ket cao duc ban hanh de ((dua tren) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: te sai ky ((lang xa) OR (lang van)) hoi. hieu ket cao duc ban hanh de ((dua tren) or (cuu tre))*.