Perhaps you should try some spelling variations:
thong cong » trong cong, tong cong, thong thong
hanh tranh » canh tranh, hanh trinh, hanh trang
hieu lang » chieu sang, hieu quang, nhieu tang
tranh cua » doanh cua, manh cua
cua thong » cua thuong, cua khong, cua tong
tac toan » tap toan, tam toan, hach toan
bai toan » bai tap
ho hieu » ho chieu, hoi hieu, nho hieu

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 - hanh tranh cua thong cong ((tac toan) or (bai toan)) cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho hieu lang - hanh tranh cua thong cong ((tac toan) OR (bai toan)) cao.
• Adding a wildcard symbol may retrieve word variants: ho hieu lang - hanh tranh cua thong cong ((tac toan) or (bai toan)) cao*.