Perhaps you should try some spelling variations:
ky lang » ky nang, ky tang, tay lang
ky dang » ky nang, ky danh
mai hoi » mai khoi, dai hoi, lai hoi
hieu ve » hieu va, hieu van
duc van » duc va, duc tan, duc manh
hoc can » hoc dan, hoc cao, hoc cac
cua tre » cua te, cuu tre, cua triet
te cac » tu cac, te cao, de cac
ve cac » va cac, vien cac
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: te cac ((ky lang) OR (ky dang)) mai hoi. hieu ve cac ((duc van) or (hoc can)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te cac ((ky lang) OR (ky dang)) mai hoi. hieu ve cac ((duc van) OR (hoc can)) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te cac ((ky lang) OR (ky dang)) mai hoi. hieu ve cac ((duc van) or (hoc can)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: te cac ((ky lang) OR (ky dang)) mai hoi. hieu ve cac ((duc van) or (hoc can)) hanh vi cua tre*.