Perhaps you should try some spelling variations:
thanh trung » thanh tung
chieu sang » chieu sach, chieu xanh, nhieu tang
nhung cong » dung cong, thong cong, hang cong
hieu lang » hieu quang, nhieu tang, hieu van
tam nhung » tham nhung, cam nhung, nam nhung
tan toan » tan tran, tap toan, van toan
bai toan » bai tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: ho ((chieu sang) or (hieu lang)) - thanh trung tam nhung cong ((tan toan) or (bai toan)) tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho ((chieu sang) OR (hieu lang)) - thanh trung tam nhung cong ((tan toan) OR (bai toan)) tap.
• Adding a wildcard symbol may retrieve word variants: ho ((chieu sang) or (hieu lang)) - thanh trung tam nhung cong ((tan toan) or (bai toan)) tap*.