Perhaps you should try some spelling variations:
thanh trung » thanh tung
thong cong » trong cong, tong cong, phong chong
hieu lang » chieu sang, hieu quang, nhieu tang
trung cua » truong cua, trung tuan, trung cap
thanh cac » hanh cac, thanh bac, thanh ca
than cap » khan cap, thanh lap, than cua
ho hieu » ho chieu, hoi hieu, nho hieu

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: ho hieu lang - thanh trung cua ((thong cong) OR (thong thong)) sang ((than cap) OR (thanh cac))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho hieu lang - thanh trung cua ((thong cong) or (thong thong)) sang ((than cap) OR (thanh cac))~".
• Adding a wildcard symbol may retrieve word variants: ho hieu lang - thanh trung cua ((thong cong) or (thong thong)) sang ((than cap) OR (thanh cac))*.