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

2) The game of rugby originated at Rugby School in England and has since evolved into different versions, including Rugby Union and Rugby League.

3) The assassination of Archduke Franz Ferdinand of Austria in 1914 triggered the start of World War I.

4) Oceans play a crucial role in regulating the Earth's climate by absorbing and storing large amounts of heat and carbon dioxide.