Why was world war 1 called the Great War

because it was "one of the deadliest conflicts"

Explanation:

"Also called The Great War, World War I was one of the deadliest conflicts in history, and set the stage for another world war just 20 years later. It was known as “The Great War”—a land, air and sea conflict so terrible, it left over 8 million military personnel and 6.6 million civilians dead."

onto a large boat, and mark the water level that the boat sinks to. then, take the elephant out and put a bunch of marked weights onto the boat until it reaches the same water level. add up the masses of the weights to get the weight of the elephant.

op: object of preposition