Perhaps you should try some spelling variations:
thanh trung » thanh tung
nhung cong » dung cong, thong cong, hang cong
hieu lang » chieu sang, hieu quang, nhieu tang
trung cua » truong cua, trung tuan, trung cap
cua nhung » va nhung
hoc hieu » hoc thieu, hoc hien, doc hieu
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: hoc hieu lang - thanh trung cua nhung cong ((tap toan) or (tap doan)) cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu lang - thanh trung cua nhung cong ((tap toan) OR (tap doan)) cao*.