Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
ban thanh » ban hanh, ban hang
cua tre » cua te, cuu tre, cua triet
duc ban » duc tan, duc van, dua ban
hieu va » lieu va, hieu qua
hieu ve » hieu van
tang ma » mang may, tang van
ky tang » ky nang, ky dang, kho tang
ma hoi » mai hoi, xa hoi, ma hoa
su cac » tu cac, su cao, su can
su sac » su sach, 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) OR (su cac)) ky tang ma hoi. ((hieu ve) or (hieu va)) pham duc ban thanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sac) OR (su cac)) ky tang ma hoi. ((hieu ve) OR (hieu va)) pham duc ban thanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sac) OR (su cac)) ky tang ma hoi. ((hieu ve) or (hieu va)) pham duc ban thanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sac) OR (su cac)) ky tang ma hoi. ((hieu ve) or (hieu va)) pham duc ban thanh dai cua tre*.