Perhaps you should try some spelling variations:
nang dai » nang tai, lang dai, nang cai
hanh hai » thanh hai, nhanh hai, hang hai
nang dau » hang dau, xang dau, nang du
cua tre » cua te, cuu tre, cua triet
cac luc » cau luc, coc luc, cac nuoc
hai cua » thai cua, dai cua, hoi cua
hieu ve » hieu van
va hanh » van hanh, va thanh, va danh
hieu va » lieu va, hieu qua
luc va » duc va, tuc va, loc va
su sac » su sach, su cac, su xac
sac ky » cac ky, sai ky

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