Perhaps you should try some spelling variations:
hoc quoc » hoc nuoc, hoc duoc, hoc thuoc
cua tre » cua te, cuu tre, cua triet
cac xuc » cam xuc, cac nuoc, chat xuc
hieu ve » hieu va, hieu van
vi cua » vai cua, di cua
dan vi » doan vi, don vi, dan va
va dan » ca dan, va dao, va dau
tu san » thu san, tu can, vu san
tu ban » thu ban, te ban
va xa » va xac, va xay, va xu
my va » may va, ly va, me va

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu san) or (tu ban)) my va xa hoi. hieu ve ((cac xuc) or (hoc quoc)) va dan vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu san) OR (tu ban)) my va xa hoi. hieu ve ((cac xuc) OR (hoc quoc)) va dan vi cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu san) or (tu ban)) my va xa hoi. hieu ve ((cac xuc) or (hoc quoc)) va dan vi cua tre*.