For much of military history, battle was a continuous struggle between weaponry and protective systems: spear and shield, sword and mail, shell and armor. 对于大部分的军事历史来说,战场就是攻击武器与防卫系统持续不断的斗争:长矛与盾牌,利剑与盔甲,炮弹与装甲。
The social, political, economic, cultural, scientific and technological changes in the environment as well as advanced communication, marketing theory and the introduction of continuous improvement. In recent decades, especially in coastal cities, Direct Mail Media has been rapid development. 由于社会政治、经济、文化、科技环境的改变以及先进传播、营销理论的引进和不断完善,近几十年,尤其是在沿海发达城市,直邮传媒得到了突飞猛进的发展。