Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, lieu vien
vien cach » vien bach, vien cac, vien canh
cac phoi » cac thoi, cac khoi, cap phoi
cach hoc » cach thuc, cach thoi, dich hoc
tinh hai » tinh thai, tinh chat, trinh han
va tinh » may tinh
hai cua » thai cua, dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
ky va » ly va, my va, ky la
ke va » te 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 cac ((ky va) or (ke va)) cac phoi. hieu vien cach hoc va tinh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu cac ((ky va) OR (ke va)) cac phoi. hieu vien cach hoc va tinh hai cua tre.
• Adding a wildcard symbol may retrieve word variants: tu cac ((ky va) or (ke va)) cac phoi. hieu vien cach hoc va tinh hai cua tre*.