举出以下四种电磁波在人们生活、生产中应用的事例（每种电磁波各举一例）．

示例：红外线：电视机遥控器利用红外线进行遥控

（1）无线电波：______；

（2）微 波：______；

（3）γ射线：______；

（4）X射线：______．

我们在充分享受电磁波给我们带来的各种方便的同时，也不要忘记电磁波也会给我们带来负面效应，请你试举出一事例加以说明．

Cooperation is the common endeavor of two or more people to perform a task or reach a jointly cherished goal. Like competition and conflict, there are different forms of cooperation, based on group organization and attitudes.
In the first form, known as primary cooperation, group and individual unite. The group contains nearly all of each individual’s life. The rewards of the group’s work are shared with each member. There is an interlocking identity of individual, group, and task performed. Means and goals become one, for cooperation itself is valued.
While primary cooperation is most often characteristic of preliterate societies, secondary cooperation is characteristic of many modern societies. In secondary cooperation, individuals devote only part of their lives to the group. Cooperation itself is not a value. Most members of the group feel loyalty, but the welfare of the group is not the first consideration. Members perform tasks so that they can separately enjoy the fruits of their cooperation in the form of salary, prestige, or power. Business offices and professional athletic teams are examples of secondary cooperation.
In the third type, called tertiary cooperation or accommodation, latent conflict underlies the shared work. The attitudes of the cooperating parties are purely opportunistic; the organization is loose and fragile. Accommodation involves common means to achieve antagonistic goals; it breaks down when the common means cease to aid each party in reaching its goals. This is not, strictly speaking, cooperation at all, and hence the somewhat contradictory term antagonistic cooperation is sometimes used for this relationship.

Which of the following is an example of the third form of cooperation as it is defined in Paragraph 4

A. Students form a study group so that all of them can improve their grades.
B. A new business attempts to take customers away from an established company.
C. Two rival political parties temporarily work together to defeat a third party.
D. Members of a fanning community share work and the food that they grow.