for做介词通常是指向对象的,例如can you do that for me?
而of则表示从属关系。the book is one of mine.
在用法上:(it's+adj for/of sb.to do sth.)
当用for的时候表示做某事对sb.来说是怎么怎么的...eg:it's good for you not to eat junk food.不吃垃圾食品对你(for)有好书
当用of的时候表示sb. 做某事是怎么怎么的...即:这件事是sb.做的,动作是sb.发出的eg.it's so nice of you to help me review the lessons.你帮我复习功课实在是太nice了