Answer:
They created the wheel and they created levees to hold back the floods from their fields and cut canals to channel river water to the fields
Explanation:
True, President Abraham Lincoln issued the Emancipation Proclamation on January 1, 1863, as the nation approached its third year of bloody civil war. The proclamation declared "that all persons held as slaves" within the rebellious states "are, and henceforward shall be free."
This would be the Works Progress Administration, which not only gave many people jobs, but also provided much needed advancements to infrastructure in the US.
The expert systems work in very limited domains.<span>Expert systems model human knowledge as a set of rules that collectively are called the knowledge base.
</span>It is a centralized repository for information that<span> holds all the </span>knowledge<span> of the </span>system<span>.</span>
The expert systems use this knowledge base to solve complex problems by reasoning.