What was thomas edison's first invention?

Ineed asap! ! what is the name of the system in which each branch of the u.s government can limit the actions of the other branches? a. perpetual union b. division of powers c. cooperative federalism d. checks and balances

Explain why american modernist writers might have perceived the world as chaotic in the early part of the 20th century. should be at least 250 words.

While the roman empire was periodically beset by invasions of nomadic peoples, the han dynasty remained uninvaded by enemies. true or false?