a.

A group is a combination of two or more interacting, interdependent individuals get together to work on a task or achieve a particular goal. 

b.

interdependence, common goal, group personality, commitment,cohesiveness, group conflict, social facilitation, gender differences, group size and norms.

c.

1. reasonable composition group members. 

2. group should have a clear division of labor. 

3. group cooperation must be premised on autonomous learning. 

4. teach students appropriate communication rules. 

5. Promote the efficiency and effectiveness of group cooperation through effective evaluation tools. 

6. forms of cooperation are diverse.