Perhaps you should try some spelling variations:
thanh trung » thanh tung
trung hoc » trung quoc
hang cong » dang cong, hang nong, bang cong
hoc hang » hoc hanh, hoc bang, hoc tang
cong san » cong tac
toan cau » toan ban, toan tap, toan tai
toan cao » toan ban, toan tap
ho hieu » ho chieu, hoi hieu, nho hieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ho hieu qua - thanh trung hoc hang cong san ((toan cau) or (toan cao))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho hieu qua - thanh trung hoc hang cong san ((toan cau) OR (toan cao)).
• Adding a wildcard symbol may retrieve word variants: ho hieu qua - thanh trung hoc hang cong san ((toan cau) or (toan cao))*.