a thirteen-year-old girl的意思|示意

She is a thirteen-year-old girl.

她是一个13岁的女孩。

A thirteen-year-old girl from Kentucky wrote me to say that I'd made a mistake, but I couldn't quit, because my opponents were mean.

肯塔基的一个13岁女孩写信给我说，虽然我犯了一个错误，但我不能辞职，因为我的敌人是卑鄙的。

Let me put it more clearly, since no one will believe that a thirteen year-old girl is completely alone in the world.

让我说的更明白点儿吧，由于没有人会相信一个13岁的女孩儿在这个世界上是完全无依无靠的，而我的确也不是。