The author says a caisson is kept free of water

because it is like

The purpose of the comintern was a. to spy on anti-communist activity. b. to spread communism in other countries. c. to administer communist rule. d. to develop future communist leaders.

How did people in the 14th century understand black death

What happened when spain’s government could not overcome social and economic problems during the great depression? citizen groups revolted against the government. the head of the government gave his resignation. a new leader seized control from the military rulers. the army led a rebellion against the government.