Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
ky tang » ky nang, ky dang, kho tang
tang xa » trang xa, tang ma, lang xa
hieu va » lieu va, hieu qua
ve cac » va cac
tu ban » thu ban, te ban
tuc va » thuc va, truc va, tuc xa
ban ky » van ky, dan ky
luc va » duc va, loc va
va cam » va cham, va cac, va cao

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ban ky tang xa hoi. hieu va cam ((luc va) OR (tuc va)) trinh ((ve cac) or (vien cac)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ban ky tang xa hoi. hieu va cam ((luc va) OR (tuc va)) trinh ((ve cac) OR (vien cac)) tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ban ky tang xa hoi. hieu va cam ((luc va) OR (tuc va)) trinh ((ve cac) or (vien cac)) tren".
• Adding a wildcard symbol may retrieve word variants: tu ban ky tang xa hoi. hieu va cam ((luc va) OR (tuc va)) trinh ((ve cac) or (vien cac)) tren*.