Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
toc sac » toc sach, toc san, hoc sach
cuu tre » cau tren, cau treo
dan vai » dan va, dan tai, dan vat
thuc va » thuc vat, thuc dan, thuc day
cua tre » cua te, cua triet, dua tren
hieu va » lieu va, hieu qua
ky dang » ky nang, ky danh
ky lang » ky nang, ky tang, tay lang
va dan » ca dan, va dao, va dau
va nam » van nam, ha nam, va nay

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sac ((ky lang) or (ky dang)) xa hoi. hieu va nam thuc va dan vai ((cuu tre) OR (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sac ((ky lang) OR (ky dang)) xa hoi. hieu va nam thuc va dan vai ((cuu tre) OR (cua tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sac ((ky lang) or (ky dang)) xa hoi. hieu va nam thuc va dan vai ((cuu tre) OR (cua tre))".
• Adding a wildcard symbol may retrieve word variants: toc sac ((ky lang) or (ky dang)) xa hoi. hieu va nam thuc va dan vai ((cuu tre) OR (cua tre))*.