He recognized his friend of many years ago.这里为什么有个of?

He recognized his friend of many years ago.这里为什么有个of? many inventins_____ hundreds of years ago 填空his father___three years ago.when he thought of his father many foods like the foods of many years ago dinosaurs________millions of years ago a friend of he和a friend of his哪个对?有什么区别? Problems must first of all be recognized.这里first of all为什么是插 these are food kike the food of many years ago these are food like the food of many years ago Many years ago,my friend went to Britain for his holidays 英语翻译that happened a couple of years of years ago.这里的a couple For many years the motive power of train be steam这里面为什么用be