1) Dwayne "The Rock" Johnson is an American actor, producer, and former professional wrestler. He has become one of the highest-paid actors in Hollywood, known for his roles in films such as the "Fast & Furious" franchise, "Jumanji," and "Moana."

2) The Great Wall of China is not visible from space without aid, contrary to popular belief.

3) The concept of 3D printing, also known as additive manufacturing, was first introduced in the 1980s and has since revolutionized prototyping and small-scale production.

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