Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc anh
nam thuc » nam thuoc, am thuc, nam thu
cau treo » cau theo, cau tren, cau triet
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
hoc cac » hoc cao
hieu ha » hieu hoa, hieu va, hieu xa
hieu ca » hieu cac, hieu cua, hieu va
thuc va » thuc vat, thuc dan, thuc day
dan vai » dan va, dan tai, dan vat
vai cau » va cau, van cau, vai cac
va dan » ca dan, va dao, va dau

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) or (hoc cac)) ky lang xa hoi. ((hieu ha) OR (hieu ca)) nam thuc va dan vai cau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc sach) OR (hoc cac)) ky lang xa hoi. ((hieu ha) OR (hieu ca)) nam thuc va dan vai cau treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc sach) or (hoc cac)) ky lang xa hoi. ((hieu ha) OR (hieu ca)) nam thuc va dan vai cau treo".
• Adding a wildcard symbol may retrieve word variants: ((hoc sach) or (hoc cac)) ky lang xa hoi. ((hieu ha) OR (hieu ca)) nam thuc va dan vai cau treo*.