Perhaps you should try some spelling variations:
thuc dan » thuc hanh, hoc dan, thuc vat
lam thuc » lam thuoc, am thuc, nam thuc
tu sach » thu sach, su sach, te sach
hanh di » hanh de, hang di, danh di
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
ky tang » ky nang, ky dang, kho tang
ky lang » ky nang, ky dang, tay lang
va lam » van lam, va lap

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 ((ky lang) or (ky tang)) xa hoi. hieu va lam thuc dan ((hanh di) OR (hanh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky lang) OR (ky tang)) xa hoi. hieu va lam thuc dan ((hanh di) OR (hanh vi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ky lang) or (ky tang)) xa hoi. hieu va lam thuc dan ((hanh di) OR (hanh vi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky lang) or (ky tang)) xa hoi. hieu va lam thuc dan ((hanh di) OR (hanh vi)) cua tre*.