The correct answer is option D. "Companies replaced hand-operated brakes with air brakes on trains". The development of air brakes on trains was a significant improvement of railroad safety. Air brakes function much more faster than hand-operated brakes, because hand-operated brakes required that the brakemen turned the brakes in one car and jump to the next to set the brakes on, and so on.
Answer:
The 369th Infantry Regiment, "Harlem Hellfighters," were a unit made of African Americans (to be PC) and were well known for their ferociousness in battle. They fought in both WW1 and WW2, and they spent the most time in combat in WW1 than any other unit (remember, America joined the war in 1917!)
Their effect on the war effort couldn't be understated, that even the Germans acknowledged them, referring to them as "Höllenkämpfer" (German for Hell Fighters) and earned the nickname "Men of Bronze" by the French (Hommes de Bronze).
Answer:
Columbus traveled to the Western hemisphere or the so-called landfall controversy.
There are two interpretations of this:
1) It was a "gift" to Ukraine, marking the amicable relations between Ukraine and the Soviet Union, to bring them even closer
2) It made the Ukrainian Soviet Socialist Republic more ethnically Russian; which would shift the dynamics in it and tie it even closer to Soviet Union (And for example make it less likely that it would try to split )
