他20岁,是he's twenty year old还是he's twenty years old

他20岁,是he's twenty year old还是he's twenty years old
他20岁,是he's twenty year old还是he's twenty years old

他20岁,是he's twenty year old还是he's twenty years old
he is a twenty-year old youngman
he is twenty years old
注意区别 前一个用单数 前置

he's twenty years old

he's twenty years old

he is 20 years old
he is a 20-year-old man

He is twenty years old.
He is twenty-year-old.

he's twenty years old

He is twenty years old.

he's twenty years old

当然是 he's twenty years old 才对。year 是可数名词，而且已经超过1，所以要+s。

he's twenty years old