1) The United States operates under a two-party system, with the Democratic Party and the Republican Party being the two major political parties that compete in elections and shape the country's political landscape.

2) The longest English word is "pneumonoultramicroscopicsilicovolcanoconiosis," which refers to a lung disease caused by inhaling very fine silica dust.

3) The role of lobbyists in politics involves representing the interests of specific groups or industries and advocating for favorable policies or influencing decision-making processes within government institutions.

4) The word "oxygen" contains two vowels: O and E.