逝去的青春岁月会让人感到些许遗憾，但满载着计划和成就进入50岁却标志着生命黄金期的到来。

AFTER a scintilla of regret over lost youth, to turn 50 should be to enter the prime of life, with a plenitude of projects and achievements.

youdao

但是青春期的首个标志之一就是毛发长在曾经不会长的地方。

But one of the first signs of puberty is hair growing where it didn't grow before.

youdao

关键是能不能找到青春期开始的标志，让人真正信服。

The key is to find a more reliable marker of puberty.

youdao