Perhaps you should try some spelling variations:
thanh trung » thanh tung
cong thanh » dong thanh, cong trinh, cong tan
hieu lang » chieu sang, hieu quang, nhieu tang
trung cua » truong cua, trung tuan, trung cap
cua thong » cua thuong, cua khong, cua tong
cong san » cong tac
than cau » toan cau, phan cau, than cap
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 lang - thanh trung cua thong ((cong san) or (cong thanh)) ((than cau) or (toan cao))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho hieu lang - thanh trung cua thong ((cong san) OR (cong thanh)) ((than cau) OR (toan cao)).
• Adding a wildcard symbol may retrieve word variants: ho hieu lang - thanh trung cua thong ((cong san) or (cong thanh)) ((than cau) or (toan cao))*.