1) The word "piano" contains three vowels: I, A, and O.

2) The Amazon rainforest produces more than 20% of the world's oxygen.

3) Antarctica is the coldest, driest, and windiest continent on Earth. It is also the highest, with an average elevation of about 7,545 feet (2,300 meters).

4) The Mona Lisa, painted by Leonardo da Vinci, is one of the most famous and valuable artworks in the world.