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

2) The highest-grossing film of all time is "Avengers: Endgame," which has earned over $2.79 billion at the global box office.

3) In Chinese mythology, the Dragon Boat Festival (also known as Duanwu Festival) is celebrated to honor Qu Yuan, a poet and statesman of ancient China. It involves dragon boat races, eating sticky rice dumplings (zongzi), and performing rituals to ward off evil spirits and protect against diseases.

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.