Answer:
Electricity and the light bulb. The electricity because thanks to the invention many people were able to communicate more and it was first used for so many other inventions on the way. The light bulb became VERY important and especially for everyday convenience since the invention around 1802..it is said that there's about 20 light bulb inventors (Thomas Edison was just credited). steam power and electricity as well.
Answer:
Britain, France, and the soviet union agreed to contain Hitler's power in Europe.
