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

2) The Battle of Waterloo in 1815 marked the final defeat of Napoleon Bonaparte and the end of his reign as Emperor of France.

3) Chinese mythology, deeply intertwined with Chinese culture and history, includes deities such as the Jade Emperor, Guanyin, and the Monkey King (Sun Wukong). It incorporates elements of Taoism, Confucianism, and Buddhism and features legendary creatures like dragons, phoenixes, and Qilin.

4) The phenomenon known as "black holes" occurs when matter is crushed into an infinitely small space, creating a gravitational pull so strong that nothing can escape.