Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
thi hong » thi cong, thi phuong, thi hanh
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan, thuc day
va danh » va dinh, va dan, va hanh
te sach » toc sach
va nam » van nam, ha nam, va nay
vai va » mai va, hai va, lai va
dai va » mai va

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ((thi thanh) or (thi hong)) cau hoi. hieu va nam thuc va danh ((vai va) OR (dai va)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((thi thanh) OR (thi hong)) cau hoi. hieu va nam thuc va danh ((vai va) OR (dai va)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((thi thanh) or (thi hong)) cau hoi. hieu va nam thuc va danh ((vai va) OR (dai va)) triet".
• Adding a wildcard symbol may retrieve word variants: te sach ((thi thanh) or (thi hong)) cau hoi. hieu va nam thuc va danh ((vai va) OR (dai va)) triet*.