青春它不属于你的永远，也不属于我的永远，注定了它只是我们人生当中的一段记忆。

Youth, it does not belong to you forever, also don't belong to me forever, it is doomed to be just a memory in our life.

youdao

Already from this class if I told you that I gave you energies in some spectrum but they were off by a factor of four, what would you think? Maybe the Z is wrong.

从这节课开始,如果我告诉你我给了你,在某些光谱里的能量,但它们不属于四大元素之一，你会怎么想？也许Z是错的。

麻省理工公开课 - 固态化学导论课程节选