he is 18 years old.为什么year要加S

He is twelve years old. Is he( ) 14 years old? he is 20 years old,i am 15 years old.合并为一句 请教语法知识,he is four years old!he is four years old,这句话中four years 是什么成分?可否理解为修饰形容词old的状语? He is eleven years old,对eleven years old, he is 18 years old.为什么year要加S Bob is 18 years old.Mike is 19 years old.合并为一句 He is only four years old.是什么意思? he is only five years old . He is twelve years old 提问 He is forty years old.两种 HE IS 18 YEARS OLD.HE IS _ _ BOY.同义句转换 翻译He is 20 years old / years of age. He is fourteen years old同义句He is () () boy he is 16 years old.(同义句） he is ( ) ( ) ( ). MY cousin is a boy.HE is eight years old.合并为一句 my best friend is a boy he is eleven years old 合并为一句 He is over sixty years old.的同义句He is ()() sixty years old.