Perhaps you should try some spelling variations:
chat thuc » thuat thuc, nhan thuc, chat thai
thuc van » thuc vat, thuc dan, thuc va
thi hanh » thi thanh
hanh cau » nhanh cau, hang cau, hanh cac
hieu cao » chieu cao, hieu cac, kieu cao
hanh dai » hanh tai, hanh dao, vanh dai
van hanh » van thanh, ban hanh, van anh
sach thi » sach thu, sach tai, sach thieu
tu sach » thu sach, su sach, te sach
su tien » su kien, su hien, tu tieng
so viet » hoc viet
hieu ca » hieu cac, hieu cua, hieu va

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach thi hanh cau hoi. ((hieu cao) OR (hieu ca)) chat thuc van hanh dai ((su tien) or (so viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thi hanh cau hoi. ((hieu cao) OR (hieu ca)) chat thuc van hanh dai ((su tien) OR (so viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach thi hanh cau hoi. ((hieu cao) OR (hieu ca)) chat thuc van hanh dai ((su tien) or (so viet))".
• Adding a wildcard symbol may retrieve word variants: tu sach thi hanh cau hoi. ((hieu cao) OR (hieu ca)) chat thuc van hanh dai ((su tien) or (so viet))*.