历史像一条长河,它川流不息,为了识别它就必须树立许多里程碑,把一条长河标成为许多段落。各个段落的条件不同,人们就在各个不同条件下建立了各种形式的关系,进行斗争和生活。各个重大的历史事件就在这些不同背景下发生和发展着。因此, History is like a long river, it flows continuously, in order to identify it, we must establish many milestones, a long river into many paragraphs. Under different conditions in different paragraphs, people have established various forms of relations, struggles and lives under various conditions. Each major historical event happened and developed under these different backgrounds. therefore,