Perhaps you should try some spelling variations:
cao hoi » cau hoi, co hoi, cao hoc
hieu ve » hieu va, hieu van
cac toc » cac toi, cac nuoc, cac thoi
ban cau » bang cau, ban can, van cau
sac ky » sai ky
ve cac » va cac, vien cac
toc va » hoc va, toc ta, tuc va
va dan » ca dan, va dao, va dau
ca cau » cua cau, cac cau, can cau

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sac ky) or (cac ky)) nang cao hoi. hieu ve cac toc va dan ((ca cau) or (ban cau)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sac ky) OR (cac ky)) nang cao hoi. hieu ve cac toc va dan ((ca cau) OR (ban cau)) tren.
• Adding a wildcard symbol may retrieve word variants: tu ((sac ky) or (cac ky)) nang cao hoi. hieu ve cac toc va dan ((ca cau) or (ban cau)) tren*.