What were the major achievement of middle age of human society define any three of them in brief

Chris would like to conduct a study on the effectiveness of a new substance-abuse treatment program. he has a sample of participants go through the program and he uses as a comparison group people who did not volunteer for the program but were eligible. chris has used a(n) design for his study.

In at least two paragraphs, discuss the differences between the principles of republicanism and democracy. explain whether you think the united states is more of a republic or a democracy. refer to at least one example from the constitution. (10 points)

Humans are the only animals capable of communication