1) The first successful human heart transplant was performed by Dr. Christiaan Barnard in 1967.

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

3) Michael Phelps, an American swimmer, has won a total of 28 Olympic medals, including 23 gold medals, making him the most decorated Olympian of all time.

4) The word "island" contains two vowels: I and A.