Perhaps you should try some spelling variations:
hieu manh » chieu xanh, hieu nganh, dieu hanh
hoc hieu » hoc thieu, hoc hien, doc hieu
cong dan » cong san, cong tan, huong dan
cong tac » cong ty
toan cao » toan ban, toan tap
tung ha » trung ha, dung ha, tang ha
tung ho » tuong ho, trung hoc, trung hoa

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 manh - thanh ((tung ha) OR (tung ho)) nhung ((cong dan) or (cong tac)) toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu manh - thanh ((tung ha) OR (tung ho)) nhung ((cong dan) OR (cong tac)) toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hieu manh - thanh ((tung ha) OR (tung ho)) nhung ((cong dan) or (cong tac)) toan cao".
• Adding a wildcard symbol may retrieve word variants: hoc hieu manh - thanh ((tung ha) OR (tung ho)) nhung ((cong dan) or (cong tac)) toan cao*.