1) The President of the United States serves as the head of state and the head of government, responsible for leading the executive branch and representing the nation domestically and internationally.

2) The first photograph of a black hole was captured in 2019 using a network of telescopes around the world.

3) The Industrial Revolution led to significant urbanization, as people migrated from rural areas to cities in search of employment in factories.

4) The Great Wall of China is not visible from space without aid, contrary to popular belief.