The main reason for economic failure of the soviet union was

It could not send in Soviet troops to put down the rebellions against communism in Eastern Europe because such an action would have resulted in a refusal of Western sources to lend the money needed. Gorbachev's failure to implement effective reforms led to Russian nationalism which yeltsin exploited.

Explanation:

for the 2 countries u can do china and america because america has a democratic government while china has a communist government.

a democracy is a government run by the people either by directly voting or indirectly by electing representatives. an oligarchy is a government run by a few or a small group of people. a democracy and oligarchy are similar because both in an oligarchy and an indirect democracy, a small group of induvial determine the laws for a large group of people they are different because in an oligarchy it is easier to control and they do not have to answer to a large number of people in the country, unlike a democracy where they do have to answer to a large number of people an county that is a democracy would be the united states. a country that is an oligarchy would be the china.