Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
thuc day » thuc dan, thuc vat
hoc sach » hoc sinh, hoc cac, hoc anh
cac thuc » cach thuc, cac thu, can thuc
qua cac » cua cac
ty nang » ky nang, ty hang, ly nang
xanh di » danh di, vanh dai, xanh tai
hanh ve » hanh vi, hanh va, hanh kem

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach ((ty nang) OR (ty xang)) xa hoi. hieu qua cac thuc day ((xanh di) or (hanh ve)) cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ((ty nang) OR (ty xang)) xa hoi. hieu qua cac thuc day ((xanh di) OR (hanh ve)) cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ((ty nang) OR (ty xang)) xa hoi. hieu qua cac thuc day ((xanh di) or (hanh ve)) cua triet".
• Adding a wildcard symbol may retrieve word variants: hoc sach ((ty nang) OR (ty xang)) xa hoi. hieu qua cac thuc day ((xanh di) or (hanh ve)) cua triet*.