Perhaps you should try some spelling variations:
hieu ve » hieu va, hieu van
cao duc » dao duc, cao suc, giao duc
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky
nang o » nang co, nang ho, nang ro
ve cao » va cao, ve bao, ve cac
o hoi » co hoi, o hoc, o hai

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 nang o hoi. hieu ve cao duc ((va hanh) or (may tinh)) dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky nang o hoi. hieu ve cao duc ((va hanh) OR (may tinh)) dai cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sac ky nang o hoi. hieu ve cao duc ((va hanh) or (may tinh)) dai cua tre*.