Perhaps you should try some spelling variations:
mai hoi » mai khoi, dai hoi, mai doi
lai hoi » dai hoi, lai hoa, lai roi
hieu ve » hieu va, hieu van
anh tri » anh thi, anh tai, thanh tri
cua tre » cua te, cuu tre, cua triet
su cac » tu cac, su cao, su can
ve cac » va cac, vien cac
dac va » day va, dat va, dai va

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

• If you are trying to use Boolean operators, they must be ALL CAPS: su cac ky nang ((mai hoi) OR (lai hoi)). hieu ve cac ((dac va) OR (duc va)) anh tri cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su cac ky nang ((mai hoi) or (lai hoi)). hieu ve cac ((dac va) OR (duc va)) anh tri cua tre~".
• Adding a wildcard symbol may retrieve word variants: su cac ky nang ((mai hoi) or (lai hoi)). hieu ve cac ((dac va) OR (duc va)) anh tri cua tre*.