Physiologists ran tests, showing, proving scientifically the limit of human ability was running the mile in 4 minutes.

生理学家进行实验，在科学上展示证明人类能力极限,是四分钟跑一英里。

哈佛公开课 - 幸福课课程节选

In fact, doctors proved the 4 minutes for the mile was the limit of human ability.

事实上医生证明四分钟跑一英里,是人类能力的极限。

哈佛公开课 - 幸福课课程节选