1) The first modern health insurance policy was introduced in Germany in the late 19th century.

2) The smallest unit of time is known as a zeptosecond, which is equal to one trillionth of one billionth of a second.

3) 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.

4) The word "telephone" contains five vowels: E, E, O, E, and E.