8.Kate is an eight-years-old boy.这里为什么year还要加s,不是有横线就不用加吗?还有

8.Kate is an eight-years-old boy.这里为什么year还要加s,不是有横线就不用加吗?还有 an eight-year-old boy为什么year不加s 这属于什么语法 he is 18 years old.为什么year要加S 为什么是she is an eight-year-old girl?she is an eight-years-old a girl of 后面加eight years old还是eight-year-old?为什么,麻烦详细一点 Deenie is about a thirteen-year-old girl.中的year为什么不用加s? 为什么Six Years Old.中Year要加S呢? she is an eight years old 还是she is an eight-year-old girl对 Jane is an eight-year-old girl.改同义句 It's five years since he Benny is an eight-year-old boy 相同的句子 Kate is ten years old.Lily is eight years old. 像an eight-year-old girl之类要加old,那an eight hundred-word articl