It seems that man was making a real effort to understand the seasons 20,000 years earlier than has been supposed中than前后的
问题描述：
It seems that man was making a real effort to understand the seasons 20,000 years earlier than has been supposed中than前后的时态 不一样 求分析
答
这句是在 has been supposed 前省略了 what
意思是人类似乎早就在关注并尝试了解季节（的变化）,比原先设想的还早了2万年.