The World Health Organization is working to improve public health worldwide.

The Paleolithic is the first era of human history.

The Bronze Age was an important period in human history.

The Neolithic was an important period in human history.

The Mesolithic is the era between the Paleolithic and the Neolithic.

The Azuchi-Momoyama period, also known as the Oda-Nobunaga period, was a very important time in Japanese history.

The Azuchi-Momoyama period was a very important time in Japanese history.

World War I was a large-scale war that lasted from 1914 to 1918.

World War II lasted from 1939 to 1945.

Let's pray that World War III does not occur.