Why did Stalin shoot his own generals?

List three reasons why explorers began to explore new, and old areas. [[ps: doesn't explicitly say where. i think it's more in general.

Select the five weaknesses of the articles of confederation. congress could not declare war or establish an army. congress could not levy taxes. congress could not control trade. not all the states were represented in congress. no national court system. no executive to enforce the laws. congress could not negotiate with foreign governments. the national government could not borrow money. nine of the states had to agree to pass a law.

The louisianna purchase was controversil because