Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
kho tang » cao tang
hieu ve » hieu va, hieu van
duc van » duc va, duc tan, duc manh
duc ban » duc tan, dua ban, duc man
ve pham » vi pham, v pham, ve phan
cua tre » cua te, cuu tre, cua triet
ky tang » ky nang, ky dang, ky trong
ma hoi » mai hoi, xa hoi, ma hoa
su sac » su sach, su cac, su xac

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sac ((ky tang) or (kho tang)) ma hoi. hieu ve pham ((duc ban) OR (duc van)) thanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sac ((ky tang) OR (kho tang)) ma hoi. hieu ve pham ((duc ban) OR (duc van)) thanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sac ((ky tang) or (kho tang)) ma hoi. hieu ve pham ((duc ban) OR (duc van)) thanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: su sac ((ky tang) or (kho tang)) ma hoi. hieu ve pham ((duc ban) OR (duc van)) thanh dai cua tre*.