Perhaps you should try some spelling variations:
hieu vien » hieu hien, thieu nien, hieu tieng
hieu viec » nhieu viec, hieu ve, sieu viet
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
cua tre » cua te, cuu tre, cua triet
nang ma » sang ma, nang cao, mang may
danh vi » hanh vi, dinh vi, danh di
tang ma » mang may, tang van
va danh » va dinh, va dan, va hanh
vi cua » vai cua, di cua
vu sac » vu sach, vu san, va sac
sac ky » cac ky, sai ky

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sac ky ((nang ma) or (tang ma)) hoi. ((hieu vien) OR (hieu viec)) cac nuoc va danh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sac ky ((nang ma) OR (tang ma)) hoi. ((hieu vien) OR (hieu viec)) cac nuoc va danh vi cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sac ky ((nang ma) or (tang ma)) hoi. ((hieu vien) OR (hieu viec)) cac nuoc va danh vi cua tre*".