Perhaps you should try some spelling variations:
chat thuc » thuat thuc, nhan thuc, chat thai
hieu van » hieu va, thien van, lieu va
van chat » cao chat
vai cua » dai cua, hai cua, lai cua
don vai » don vi, don va, den vai
thuc va » thuc vat, thuc dan, thuc day
cua tre » cua te, cuu tre, cua triet
ky tang » ky nang, ky dang, kho tang
ky lang » ky nang, ky dang, tay lang
va don » va dong, va doc, va do
tu ban » thu ban, te ban
tu can » tu cac, thu canh

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

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