1) The world's tallest waterfall is Angel Falls in Venezuela, with a height of about 3,212 feet (979 meters).

2) The NBA (National Basketball Association) is widely regarded as one of the most popular and competitive professional basketball leagues in the world.

3) The Russian Revolution in 1917 resulted in the overthrow of the monarchy and the establishment of a communist government under Vladimir Lenin.

4) The word "elephant" contains three vowels: E, A, and E.