Perhaps you should try some spelling variations:
truong trung » tieng trung
truong thanh » truong thpt, truong chung
thien hach » thien thanh, hien hanh
chieu sach » chinh sach, chiet tach, chieu sang
hang cong » dang cong, hang nong, bang cong
cong san » cong tac
san toan » van toan, dan toan, manh toan
toan cau » toan cao, toan ban, toan tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((thien hach) or (chieu sach)) - hanh ((truong thanh) OR (truong trung)) hang cong san toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thien hach) OR (chieu sach)) - hanh ((truong thanh) OR (truong trung)) hang cong san toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thien hach) or (chieu sach)) - hanh ((truong thanh) OR (truong trung)) hang cong san toan cau".
• Adding a wildcard symbol may retrieve word variants: hoc ((thien hach) or (chieu sach)) - hanh ((truong thanh) OR (truong trung)) hang cong san toan cau*.