1) The Dow Jones Industrial Average (DJIA) is a stock market index that tracks the performance of 30 large, publicly owned companies in the United States.

2) The tongue of a blue whale is so big that about 50 people could stand on it.

3) The Federal Reserve System, often referred to as the Fed, is the central banking system of the United States.

4) The Eiffel Tower can be 15 cm taller during the summer due to thermal expansion.