Perhaps you should try some spelling variations:
so sanh » do sanh
sanh ky » hanh ky, sang ky, nganh ky
va dinh » van dinh, va kinh, va tinh
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
cac duc » cao duc, cac dac, cac nuoc
hieu ve » hieu va, hieu van
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
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: so sanh ky lang xa hoi. hieu ve ((cac duc) OR (cac du)) ((va hanh) or (va dinh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sanh ky lang xa hoi. hieu ve ((cac duc) OR (cac du)) ((va hanh) OR (va dinh)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sanh ky lang xa hoi. hieu ve ((cac duc) OR (cac du)) ((va hanh) or (va dinh)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: so sanh ky lang xa hoi. hieu ve ((cac duc) OR (cac du)) ((va hanh) or (va dinh)) vi cua tre*.