sixteen-year-olds跟sixteen-year-old有以下区别： 一、sixteen-year-olds只有一种词性。

名词。因为后面加了s。同类用法只要改前面的数字。双语例句：

1、Eighteen-year-olds qualify to vote . 译文：年满十八岁者有选举权。

2、Even five-year-olds do not want a party every day. 译文：就算是5岁的孩子也不想天天聚会。

二、sixteen-year-old通常只做形容词用。双语例句：

1、Sixteen-Year-old Hans stepped forward. 译文：十六岁的汉斯向前地踏。

2、Mike is a sixteen-year-old boy. 译文：迈克是一个16岁的男孩。

可以加可以不加，只说数字的时候不加，例如，I am sixteen. 如果有year时就需要加old, 例如，I am sixteen years old.

十六岁英语后面要加old。十六岁的英文翻译是，

sixteen years old 。

Their age are under sixteen years old .

他们年龄都在16岁以下。

He is, to be exact, sixteen years old, and is not old enough to join the army.

确切地说，他才十六岁，还没达到参军的年龄。

It's 1971. He's tall and gawky and sixteen years old.

那是1971年，他高高的身材，略显笨拙，年龄是16岁。