Perhaps you should try some spelling variations:
thanh trung » thanh tung
hieu lang » chieu sang, hieu quang, nhieu tang
trung cua » truong cua, trung tuan, trung cap
ban luong » ban huong, van luong, ban muong
ban tuong » ban huong, ban trong, va tuong
bai toan » bai tap
ho hieu » ho chieu, hoi hieu, nho hieu
va toan » van toan, tap toan, va thanh

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 ((ban luong) or (ban tuong)) ((va toan) OR (bai toan)) cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho hieu lang - thanh trung cua ((ban luong) OR (ban tuong)) ((va toan) OR (bai toan)) cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho hieu lang - thanh trung cua ((ban luong) or (ban tuong)) ((va toan) OR (bai toan)) cao".
• Adding a wildcard symbol may retrieve word variants: ho hieu lang - thanh trung cua ((ban luong) or (ban tuong)) ((va toan) OR (bai toan)) cao*.