古埃及人是如何知道地球是圆的，并且计算出地球周长的
via前史之鉴的微博 https://twitter.com/williamwoo7/status/1277924172149125120/video/1 https://twitter.com/williamwoo7/status/1277924172149125120
https://t.me/private_channel_c14370a/4131
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