1) The world's longest traffic jam occurred in China in 2010 and lasted for 12 days, stretching over 60 miles (97 km).

2) The word "oxygen" contains two vowels: O and E.

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 development of blockchain technology, first introduced in 2008 with the creation of Bitcoin, has enabled secure and decentralized digital transactions and led to the emergence of cryptocurrencies.