)which of these contributed to a long period of stalemate during world war i? the threat of atomic attacks the use of trench warfare the use of machine guns the threat of chemical weapons

The use of trench warfare contributed to a long period of stalemate during World War I.

Explanation:

Trench warfare is a form of warfare, in which the fighting armies maintain static lines of fortifications dug in the ground, called trenches. Trench warfare arose from a revolution in firearms. There were periods of trench warfare in the Civil War (1861-1865) and the Russian-Japanese War of 1904-1905, but it reached its peak of brutality and mortality on the Western Front of World War I, where this type of fighting produced a stagnation of three years, until the American forces entered the war and unleashed the conflict in favor of the allies.

alliances in ww1 were different from ww2 because the entente in ww1 made up of serbia,russia,france,britan,japan and italy later america  and all allied in a sort of balance of power and too keep germany,austria-hungary,and the ottomans down. russia allied the serbians in order to exert its influence in the balkans while france allied the russians because france was still in dismay and insulted after the defeat to the germans during the unification of germany and britian allied the belgians after the germans invasion of belgium.in ww2 the alliances were in a preemptive attempt to deter any further wars into happening while germany and italy allied since they were insulted and humiliated after the previous war while also sharing a similar ideology of facsim along with japan which all 3 had a want for world domination and agreed to assist one another in the endevours 

explanation: