Perhaps you should try some spelling variations:
thuc dan » thuc hanh, hoc dan, thuc vat
dan hanh » dang hanh, dan khanh, dan thanh
hanh dai » hanh tai, hanh dao, vanh dai
cao hoi » cau hoi, co hoi, cao hoc
hieu ve » hieu van
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
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 ((sach y) or (sac ky)) nang cao hoi. ((hieu ve) OR (hieu va)) am thuc dan hanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach y) OR (sac ky)) nang cao hoi. ((hieu ve) OR (hieu va)) am thuc dan hanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach y) or (sac ky)) nang cao hoi. ((hieu ve) OR (hieu va)) am thuc dan hanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach y) or (sac ky)) nang cao hoi. ((hieu ve) OR (hieu va)) am thuc dan hanh dai cua tre*.