You yawn, and your friend yawns too.
你一打哈欠，朋友也跟着打。
Why is yawning so catchy?
哈欠这东西，为啥这么会传染？
Scientists think it is your brain's mirror.
科学家认为，这是大脑在照镜子。
When you see a yawn, your brain copies it.
你看见别人打，大脑就偷偷模仿。
It shows you understand other people.
这说明呀，你能懂别人的感受。
Even dogs can catch a human's yawn.
连小狗，都能被人的哈欠传染。
So next time, yawn back and smile.
下回被传染，就笑着打回去吧。
