Perhaps you should try some spelling variations:
thuc dan » thuc hanh, hoc dan, thuc vat
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
dao dai » dat dai, dao dan, tao dai
thuc va » thuc vat, thuc day
tang ma » mang may, tang van
hieu ve » hieu va
y tang » ky tang, 6 tang, 7 tang
cua te » cua tu

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 tang ma hoa. ((hieu ve) or (hieu van)) cam ((thuc va) OR (thuc dan)) dao dai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y tang ma hoa. ((hieu ve) OR (hieu van)) cam ((thuc va) OR (thuc dan)) dao dai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y tang ma hoa. ((hieu ve) or (hieu van)) cam ((thuc va) OR (thuc dan)) dao dai cua te".
• Adding a wildcard symbol may retrieve word variants: su sach y tang ma hoa. ((hieu ve) or (hieu van)) cam ((thuc va) OR (thuc dan)) dao dai cua te*.