Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
luoc can » luc canh, hoc can, luoc dai
vien cac » vien bach, vien dai, vien da
duc van » duc va, duc tan, duc manh
cua tre » cua te, cuu tre, cua triet
nang ma » sang ma, nang cao, mang may
tang ma » mang may, tang van
sac ky » cac ky, sai ky
vi cua » vai cua, di cua
te sac » te sach, te cac, te san

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

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