Perhaps you should try some spelling variations:
hang cau » hang dau, hang ca, nhung cau
so sanh » do sanh
sanh ky » hanh ky, sang ky, nganh ky
ky hang » ky nang, ly hang, ky dang
hieu ve » hieu van
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
tuc cac » tu cac, tich cac
va cua » va chua, via cua, ma cua
ca cua » co 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 hang cau hoi. ((hieu ve) or (hieu va)) cac tuc cac dan ((va cua) or (ca cua)) tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sanh ky hang cau hoi. ((hieu ve) OR (hieu va)) cac tuc cac dan ((va cua) OR (ca cua)) tu.
• Adding a wildcard symbol may retrieve word variants: so sanh ky hang cau hoi. ((hieu ve) or (hieu va)) cac tuc cac dan ((va cua) or (ca cua)) tu*.