This is a period of history that should not be forgotten, and is a subject that can't be neglected in population migration history of the 20th century as well.
这是一段不应忘记的历史，也是20世纪人口迁移史上一个不可忽略的课题。
The history and degree of demographic stress varies from country to country, and it should not be forgotten that by its latter years the Soviet Union had already become a demographic disaster area.
各国的历史和人口结构压力不尽相同。人们不应忘记在苏联后期，那里已经出现了人口结构灾难。但这一地区的多数国家都经历过这方面的灾难。
In China's modern history of ideas, Zhang Shenfu as a philosopher should not be forgotten.
在中国近现代思想史上，张申府是一位不应该被遗忘的哲学家。
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