Question

What did most Americans understand before their country entered World War I? that the war would not last long that the war would cost American lives that the war would help the US economy that the war could be won by the US alone

Answer 1

The war would help American economy

Answer 2

That the war would cost American lives. Whenever US enters in a war, the citizens of the country know that there is growing to be a collateral damage.

It was no different during the World War also. People knew that there was going to be heavy casualties during the war and whoever enrolds for the services they run a risk of losing their lives.

Actually, the same happened during the World war also and many Americans lost their lives in the war.