Perhaps you should try some spelling variations:
hieu quan » lieu quan, thien quan, lien quan
hanh vaia » hanh vi, hanh va, hanh tai
vaia cua » vai cua, via cua, dai cua
van hanh » van thanh, ban hanh, van anh
hoc anh » hoc nganh, hoc nhanh, ngoc anh
duc van » duc va, duc tan, duc manh
cam duc » cam xuc, cao duc, pham duc
cua tre » cua te, cuu tre, cua triet
lang xa » lang ha, dang xay, lang van
nang xa » nang x, nang ma, mang xa
anh va » hanh va

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc anh va ((nang xa) OR (lang xa)) hoi. ((hieu qua) or (hieu quan)) cam duc van hanh vaia cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc anh va ((nang xa) OR (lang xa)) hoi. ((hieu qua) OR (hieu quan)) cam duc van hanh vaia cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc anh va ((nang xa) OR (lang xa)) hoi. ((hieu qua) or (hieu quan)) cam duc van hanh vaia cua tre".
• Adding a wildcard symbol may retrieve word variants: hoc anh va ((nang xa) OR (lang xa)) hoi. ((hieu qua) or (hieu quan)) cam duc van hanh vaia cua tre*.