Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
khang te » khang tiet, hang tu, khang a
thuc dan » thuc hanh, hoc dan, thuc vat
thuc van » thuc vat, thuc va, thuc hanh
hieu van » hieu va, thien van, lieu va
van cau » van dau, van hau, van chat
tang ma » mang may, tang van
ky tang » ky nang, ky dang, kho tang
vu sach » vu bach, su sach, vu khach
tu sach » thu sach, su sach, te sach
ma hoi » mai hoi, xa hoi, ma hoa
te va » tu 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) or (vu sach)) ky tang ma hoi. hieu van cau ((thuc van) OR (thuc dan)) khang te va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (vu sach)) ky tang ma hoi. hieu van cau ((thuc van) OR (thuc dan)) khang te va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (vu sach)) ky tang ma hoi. hieu van cau ((thuc van) OR (thuc dan)) khang te va triet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (vu sach)) ky tang ma hoi. hieu van cau ((thuc van) OR (thuc dan)) khang te va triet*.