Perhaps you should try some spelling variations:
luoc can » luc canh, hoc can, luoc dai
hieu va » lieu va, hieu qua
duc van » duc va, duc tan, duc manh
cua tre » cua te, cuu tre, cua triet
dai hai » dai han, dai hoi, dai tai
tai hoi » tai khoi, dai hoi, tai hai
ky hang » ky nang, ly hang, ky dang
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 hang ((tai hoi) or (dai hai)). hieu va 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 hang ((tai hoi) OR (dai hai)). hieu va cac ((duc van) OR (luoc can)) hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: te sac ky hang ((tai hoi) or (dai hai)). hieu va cac ((duc van) or (luoc can)) hanh vi cua tre*.