Perhaps you should try some spelling variations:
thanh trung » thanh tung
phuong cong » phuong dong, phong cong, phung cong
chieu sang » chieu sach, chieu xanh, nhieu tang
hieu lang » hieu quang, nhieu tang, hieu van
va phuong » va thuong, cac phuong
trung va » truong va, trang va, trung ha
tap toan » tap quan, bai toan
tap doan » tap quan

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

• Performing a fuzzy search may retrieve terms with similar spellings: doi ((chieu sang) OR (hieu lang)) - thanh trung va phuong cong ((tap toan) or (tap doan)) cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi ((chieu sang) OR (hieu lang)) - thanh trung va phuong cong ((tap toan) OR (tap doan)) cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doi ((chieu sang) OR (hieu lang)) - thanh trung va phuong cong ((tap toan) or (tap doan)) cao".
• Adding a wildcard symbol may retrieve word variants: doi ((chieu sang) OR (hieu lang)) - thanh trung va phuong cong ((tap toan) or (tap doan)) cao*.