请教一个英语问题?a 3 -year -old boy 和a 3 years old boy 有什么区别吗?还是这两个相

请教一个英语问题?a 3 -year -old boy 和a 3 years old boy 有什么区别吗?还是这两个相 six-year-old boy和six years old boy 有什么区别?一样么?为什么? 英语问题an还是a eight-year-old boy 一个10岁的男孩是“a ten-year-old boy"还是"a ten years old boy"? a twenty year old boy对还是a twenty years old boy对 请问:是a four years old boy?还是a four year old boy?正确 a five-year-old boy与the boy is five years old的区别 a ten years old boy和a ten-year-old boy哪个对?为什么? he is a 6-year-old boy.可以说he is a 6 years old boy吗 a thirteen-year-old boy=什么? 英语问题a fifteen-year-old与a fifteen-years-old等到底有什么区别呢?我一直都没搞懂, a five-year-old boy还是a five-year old boy