Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
va hanh » van hanh, va thanh, va danh
cac hoc » cach hoc, cac hop, bac hoc
cac loc » cac lop, cac toc, cac nuoc
cua tre » cua te, cuu tre, cua triet
lang xa » lang ha, dang xay, lang van
can ky » van ky, ban ky, tan ky
dan ky » van ky
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: tu ((can ky) or (dan ky)) lang xa hoi. hieu van ((cac loc) or (cac hoc)) va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((can ky) OR (dan ky)) lang xa hoi. hieu van ((cac loc) OR (cac hoc)) va hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: tu ((can ky) or (dan ky)) lang xa hoi. hieu van ((cac loc) or (cac hoc)) va hanh vi cua tre*.