The average human heart works at 72 beats per minute. In an average lifetime, it will beat approximately 2.5 billion times.

人们的平均心跳次数是每分钟72次。在人们的平均寿命里，心脏大约跳动25亿次。

There are about 10 presidents in an average lifetime.

平均一生大约有10位总统。

We are told that if you wanted to watch every video, it would take the average American two average lifetimes to see them, so don’t even try.

我们被告知， 如果你想看每一个视频， 美国人平均要花两辈子才能看到它们，所以不要尝试。