1.A group is A small group formed or divided for the convenience of work, study, etc.A group is a collection of individuals who influence one another, derive mutual satisfaction from one another, have a common purpose, take on roles, are interdependent, and interact face-to-face

2.The characterictics of the groups include interdependence，common goal，group personality，commitment，cohesiveness，group conflict，social facilitation，gender differences，group size and norms.

Interdependence:The mutual dependence of group members on one another.

Common Goal:The driving force that brings people together to form is a common goal.

Group Personality:When people come together in a group, they form a collective identity that becomes the group personality.

Commitment:Commitment is the desire of group members to work together to complete their task to the satisfaction of the entire group.

Cohesiveness:Cohesiveness, an extension of commitment, is the attraction that group members feel for each other and their willingness to stick together.

Group Conflict:The truth of the matter is that whenever people come together in any communicative context there is bound to be conflict of some sort.

Social Facilitation：The tendency for a person to release energy that would not be released if the individual were acting alone is called social facilitation.

Gender Size：A group is composed of a number of people who are brought together or who come together voluntarily and who share a common goal, task, or purpose.

Norms：Norms are the expected and shared ways in which group members behave.

3.These eight points make the group members get into a positive participation during the group communication：Relevance,Relatedness,Timeliness,Sufficient Length,Clarity,Informativeness,Openness to evaluation and Openness to evaluation