I like the energy and the youthfulness of their music.

我喜欢他们音乐带来的能量和活力。

So my dad's last-ditch effort to regain his youthfulness isn't universal?

所以我爸爸为重返青春而做的最后努力并不是普遍的吗？

Love is the power for our youthfulness.

爱情是青春的动力。

I wonder at her perennial youthfulness.

我对她青春常驻感到惊讶。

Take time to play-it is the secret of youthfulness.

花时间游戏吧，那是年轻的秘诀。

Youthfulness can absolutely be a persistent matter!

青春的状态是绝对可以持续的！

The quality or condition of being juvenile; youthfulness.

年少年轻的特性或状态；