18岁怎么用year表示

18 years old

at the age of 18

18-year-old

1，表示多少岁，可以直接用数字：

My elder brother is 18.

我哥哥二十五岁。

2，表示多少岁，可以直接用数字+years+old：

Jane’s mother was 22 years old when she married Jane’s father.

简的母亲嫁给简的父亲时才22岁。

3，表示岁数的时候加连字符“-”，可以做形容词修饰名词或直接代替名词：

The 18-year-old boy was admitted in the university.

这个18岁的男孩被大学录取了。

This is a birthday party for 10-year-olds.

这是一个10岁的孩子们开的生日聚会。

注意，加连字符“-”，year不能用复数years

That bottle of Maotai is 25 years old.

That bottle of Maotai is 25-year-old.

那瓶茅台酒已经25年了。