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 ozone layer, located in the Earth's stratosphere, protects us from harmful ultraviolet (UV) radiation.

3) The word "music" contains two vowels: U and I.

4) The Beatles hold the record for the most number-one hits on the Billboard Hot 100 chart, with 20 songs reaching the top spot.