Perhaps you should try some spelling variations:
cang thang » cong thanh, dang thanh
hieu lang » chieu sang, hieu quang, nhieu tang
hanh hang » thanh hang, hang hang, hanh han
doi hieu » doi chieu, doc hieu, doi hien
cong dan » cong san, cong tan, huong dan
cong tac » cong ty
toan cao » toan ban, toan tap

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: doi hieu lang - ((hanh hang) OR (cang thang)) va nhung ((cong dan) OR (cong tac)) toan cao~.
• Adding a wildcard symbol may retrieve word variants: doi hieu lang - ((hanh hang) or (cang thang)) va nhung ((cong dan) or (cong tac)) toan cao*.