Man could not stay there forever. He was bound to spread to new regions, partly because of his innate migratory tendency and partly because of Nature's stern urgency.
人类不可能永远呆在那里。他注定要传播到新的地区，部分原因是他天生的迁徙倾向，部分原因是大自然的严峻紧迫性。
标签
Tendency
Bound