Perhaps you should try some spelling variations:
luoc can » luc canh, hoc can, luoc dai
ky sang » ky dang, ky tang, duy sang
tao hoi » tao khoi, tao boi, tay hoi
hieu ve » hieu va, hieu van
duc van » duc va, duc tan, duc manh
cua tre » cua te, cuu tre, cua triet
te sac » te sach, te cac, te san
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 sac ((ky sang) OR (ky nang)) tao hoi. hieu ve 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 sang) OR (ky nang)) tao hoi. hieu ve 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 sang) OR (ky nang)) tao hoi. hieu ve cac ((duc van) or (luoc can)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: te sac ((ky sang) OR (ky nang)) tao hoi. hieu ve cac ((duc van) or (luoc can)) hanh vi cua tre*.