Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan, thuc day
dau hai » dai hai, dau ha, cau hai
hai cuu » hai cua, hai chu, hai cuc
cuu tre » cua tre, cau tren, cau treo
va nay » va ngay, va cay

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sach) or (hoc sinh)) ky lang xa hoi. hieu va nay ((thuc va) or (hoc dan)) dau hai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sinh)) ky lang xa hoi. hieu va nay ((thuc va) OR (hoc dan)) dau hai cuu tre.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (hoc sinh)) ky lang xa hoi. hieu va nay ((thuc va) or (hoc dan)) dau hai cuu tre*.