1) The Amazon rainforest produces more than 20% of the world's oxygen.

2) The first successful mass-produced personal computer, the IBM PC, was introduced in 1981 and played a significant role in popularizing the use of computers in homes and offices.

3) The Boston Celtics and the Los Angeles Lakers are the most successful teams in NBA history, with a combined total of 33 championships.

4) 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.