Perhaps you should try some spelling variations:
thanh trung » thanh tung
thong cong » trong cong, thong thong, phong chong
hieu lang » chieu sang, hieu quang, nhieu tang
trung cua » truong cua, trung tuan, trung cap
tong cong » trong cong, cong cong, dung cong
nhanh cau » nhanh cay, thanh chau, nhanh ha
hoc hieu » hoc thieu, hoc hien, doc hieu
phan cau » phan dau, phan cac, phan tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc hieu lang - thanh trung cua ((thong cong) OR (tong cong)) tan ((nhanh cau) or (phan cau))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu lang - thanh trung cua ((thong cong) OR (tong cong)) tan ((nhanh cau) OR (phan cau)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hieu lang - thanh trung cua ((thong cong) OR (tong cong)) tan ((nhanh cau) or (phan cau))".
• Adding a wildcard symbol may retrieve word variants: hoc hieu lang - thanh trung cua ((thong cong) OR (tong cong)) tan ((nhanh cau) or (phan cau))*.