Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
tac vang » cac van, tac dung, tac dong
tac van » cac van, tac va, tac can
so sanh » do sanh
lang ha » long ha
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va, hieu van
sanh y » sinh y, anh y, hanh y
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: so sanh y ((nang xa) or (lang ha)) hoi. hieu ve cac ((tac van) OR (tac vang)) hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sanh y ((nang xa) OR (lang ha)) hoi. hieu ve cac ((tac van) OR (tac vang)) hanh vi cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sanh y ((nang xa) or (lang ha)) hoi. hieu ve cac ((tac van) OR (tac vang)) hanh vi cua viet".
• Adding a wildcard symbol may retrieve word variants: so sanh y ((nang xa) or (lang ha)) hoi. hieu ve cac ((tac van) OR (tac vang)) hanh vi cua viet*.