translation.en: In the animal world, if you take rats, who are hardwired to play at a certain period of their juvenile years and you suppress play -- they squeak, they wrestle, they pin each other, that's part of their play.
translation.zh: 在动物的时间，如果你拿老鼠 一些在青少年时期玩耍的老鼠 然后你压制玩耍 -- 他们互相挤压，他们互相搏斗， 他们把对方放到，那就是他们玩耍的一部分。