What do federal, unitary and confederation systems of government have in common?

donald trump is the republican president of the united states. he is the 45th president. he's important because he is the leader of the u.s.   he decides how the laws of the united states are to be enforced and chooses officials and advisors to run the executive branch. the constitution makes the president commander in chief of the nation's armed forces. he is a very important person.

traditionally, roman society was rigid. by the first century. however, the need for capable men to run rome's vast empire was slowly eroding the social barriers. the social structure of ancient rome was based on heredity, property,wealth, citizenship and freedom.