1) The Danube River, flowing through ten countries in Central and Eastern Europe, is the second-longest river in Europe. It has played a significant role in the cultural and economic development of the regions it traverses and is a popular waterway for river cruises.

2) The largest known dinosaur, Argentinosaurus, weighed around 70-100 tons and measured up to 100 feet in length.

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

4) The highest-grossing film of all time is "Avengers: Endgame," which has earned over $2.79 billion at the global box office.