Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
cua tre » cua te, cuu tre, cua triet
cao luc » bao luc, cao duc, cao suc
tai cua » thai cua, tai cuc, tri cua
va hanh » va thanh, va danh, ban hanh
hieu va » lieu va
lang ha » long ha
ky lang » ky nang, ky dang, ky tang
sai ky » sac ky
ha hoi » hoa hoi, ha noi, xa hoi
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 ha hoi. ((hieu va) OR (hieu qua)) cao luc ((va hanh) or (van hanh)) tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sai ky lang ha hoi. ((hieu va) OR (hieu qua)) cao luc ((va hanh) OR (van hanh)) tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sai ky lang ha hoi. ((hieu va) OR (hieu qua)) cao luc ((va hanh) or (van hanh)) tai cua tre".
• Adding a wildcard symbol may retrieve word variants: te sai ky lang ha hoi. ((hieu va) OR (hieu qua)) cao luc ((va hanh) or (van hanh)) tai cua tre*.