1) The global economy has experienced fluctuations and challenges, including the impact of the COVID-19 pandemic on businesses, supply chains, and employment, as well as efforts to address income inequality and promote sustainable economic growth.

2) The word "mountain" contains three vowels: O, U, and A.

3) The Sahara Desert, located in North Africa, is the largest hot desert in the world, covering an area of about 9.2 million square kilometers (3.6 million square miles). It is characterized by vast stretches of sand dunes, rocky plateaus, and extreme temperatures.

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