Perhaps you should try some spelling variations:
dang xay » dang van, van xay
cua tre » cua te, cuu tre, cua triet
va hanh » van hanh, va thanh, va danh
cac hoc » cach hoc, cac hop, bac hoc
cac loc » cac lop, cac toc, cac nuoc
hieu ve » hieu va, hieu van
mang xa » lang xa, mang may, mang cua
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 ((mang xa) or (dang xay)) hoi. hieu ve ((cac loc) OR (cac hoc)) va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sac ky ((mang xa) OR (dang xay)) hoi. hieu ve ((cac loc) OR (cac hoc)) va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sac ky ((mang xa) or (dang xay)) hoi. hieu ve ((cac loc) OR (cac hoc)) va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: te sac ky ((mang xa) or (dang xay)) hoi. hieu ve ((cac loc) OR (cac hoc)) va hanh vi cua tre*.