Modern life makes us tired, right? But research from societies in Africa and South America suggests people in the ancient world slept only 6.5 hours a night.

（法新社华盛顿23日电） 美国总统川普宣布美国将二度退出巴黎协定（Paris Agreement）后，亿万富豪彭博（Michael Bloomberg）今天宣布，他的基金会将接手资助联合国气候变化机构。

US President Donald Trump late Monday signed an executive order to pull the United States out of the Paris climate accord. The move means the United States will pull out of the Paris climate accord ...