Perhaps you should try some spelling variations:
day thanh » dao thanh, dat thanh, da thanh
thanh va » thanh van, hanh va, thanh ha
thuc day » thuc dan, thuc vat
cua tre » cua te, cuu tre, cua triet
ky sang » ky nang, ky dang, ky tang
hieu ve » hieu va, hieu van
tu bai » tu ban, tu bat, te bai
ma hoi » mai hoi, ma hoa, me hoi
va cua » va chua, via cua, ca cua
ve am » va am

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cac) OR (tu bai)) ky sang ((ma hoi) OR (xa hoi)). hieu ve am thuc day thanh va cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu cac) or (tu bai)) ky sang ((ma hoi) OR (xa hoi)). hieu ve am thuc day thanh va cua tre~".
• Adding a wildcard symbol may retrieve word variants: ((tu cac) or (tu bai)) ky sang ((ma hoi) OR (xa hoi)). hieu ve am thuc day thanh va cua tre*.