Answer:
The answer should be: Companies replaced hand-operated brakes with air brakes on trains.
Explanation:
You have to think how hard it was for trains to stop with hand operated brakes. Trains go fast, and not stopping in time can be dangerous. Hope this helped :)
The Founders created a high standard of responsibility by requiring nine states to agree.
. True it was used to kill people
Once again, Marbury vs. Madison.
