Why did the communist revolution occur in russia in 1917?

How was slavery in mesoamerica, africa, and the arab world similar? many enslaved people were forced to pledge loyalty to their owners. many enslaved people worked in exchange for protection from foreigners. many enslaved people were captured during war. many enslaved people taught and tutored children.

Why was russia drawn into a conflict with germany after ausria-hungary declared war on serbia ?

How would high tariffs hurt america? a. fewer immigrants would be able to move to america b. sales of american products to other countries would go down c. americans would sell more goods to other countries d. goods imported from other countries would cost less