Perhaps you should try some spelling variations:
nang cai » nang cao, nang cap, nang can
vanh dai » van dai, vanh tai, lanh dao
nang tai » hang tai, tang tai, sang tai
thuc dan » thuc hanh, hoc dan, thuc vat
vu sach » vu bach, su sach, vu khach
thuc va » thuc vat, thuc day
ve tham » va tham, ve cham, vi tham
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
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: vu sach ky ((nang cai) or (nang tai)) hoi. hieu ve tham ((thuc va) OR (thuc dan)) vanh dai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky ((nang cai) OR (nang tai)) hoi. hieu ve tham ((thuc va) OR (thuc dan)) vanh dai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky ((nang cai) or (nang tai)) hoi. hieu ve tham ((thuc va) OR (thuc dan)) vanh dai cua te".
• Adding a wildcard symbol may retrieve word variants: vu sach ky ((nang cai) or (nang tai)) hoi. hieu ve tham ((thuc va) OR (thuc dan)) vanh dai cua te*.