Perhaps you should try some spelling variations:
hanh tai » thanh tai, hang tai, han tai
mai khoi » mai khoa, tai khoa, cac khoi
cua tre » cua te, cuu tre, cua triet
cac tuc » cac toc, cac tu, cac tac
van tai » von tai, van tuan
hieu ve » hieu va, hieu van
mai hoi » dai hoi, lai hoi, mai doi
ky dang » ky nang, ky danh
ve cac » va cac, vien cac
sac ky » cac ky, sai ky
tuc va » thuc va, truc va, tuc xa
tu sac » tu sach, tu cac, tu san

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 dang ((mai hoi) OR (mai khoi)). hieu ve cac tuc va ((hanh tai) or (van tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky dang ((mai hoi) OR (mai khoi)). hieu ve cac tuc va ((hanh tai) OR (van tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky dang ((mai hoi) OR (mai khoi)). hieu ve cac tuc va ((hanh tai) or (van tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sac ky dang ((mai hoi) OR (mai khoi)). hieu ve cac tuc va ((hanh tai) or (van tai)) cua tre*.