1) A single bolt of lightning can heat the surrounding air to temperatures five times hotter than the surface of the sun.

2) The word "pencil" contains two vowels: E and I.

3) The Cuban Missile Crisis in 1962 brought the United States and the Soviet Union to the brink of nuclear war during the Cold War.

4) The Alps, located in Europe, are a popular destination for skiing, mountaineering, and hiking.