Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
sang dai » sang tai, lang dai, sang mai
dai hoi » dai hoc, dai hai, dai moi
va hanh » va thanh, va danh, ban hanh
hieu su » hieu sau, tieu su, hieu so
vi cua » vai cua, di cua
su cam » su nam, su cao, su can
sac ky » cac ky
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sai ky) or (sac ky)) sang dai hoi. hieu su cam xuc ((va hanh) OR (van hanh)) vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sai ky) OR (sac ky)) sang dai hoi. hieu su cam xuc ((va hanh) OR (van hanh)) vi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sai ky) or (sac ky)) sang dai hoi. hieu su cam xuc ((va hanh) OR (van hanh)) vi cua te".
• Adding a wildcard symbol may retrieve word variants: tu ((sai ky) or (sac ky)) sang dai hoi. hieu su cam xuc ((va hanh) OR (van hanh)) vi cua te*.