同学你好，该知识点来自沪江网校《英语零基础直达大学六级【双11专享班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学好
这里介绍一下2个句型的用法和区别：
用for 是因为前面的adj是来描述do后面的sth. 意为：“做…对某人(for sb)来说怎么样(adj)”
用of 的话,adj就用来形容sb的，意为：“某人做…(of sb)怎么样(adj)”
1. it is adj of sb to do,这里的形容词是形容人的性格特征的,如nice,kind clever,foolish,smart,都是形容人的,
例句：It is kind of you to help me.你能帮我太好了.（kind 形容的是you）
2. it is adj for sb to do就是普通的形容词,如hard,impossible,important
例句：It is beneficial for you to do sports.运动对你有益.（beneficial形容的是do sports）

辨析:
①“It’s +adj.+of+sb.+不定式”表示“某人(做某事)怎么样” 一般用表示人物的性格,品德.表示主观感情或态度的形容词.若形容词是描述逻辑主语(行为者即of后的sb)的性格、品质特征的形容词. 这个adj.是用来形容sb.的.
of后的宾语能与前面的形容词构成主表关系. 这类形容词有:
good(好的),kind(友善的),
nice(友好的),polite(有礼貌的),
clever(聪明的),foolish(愚蠢的),
lazy(懒惰的), right(正直的)
careful(细心的),careless(粗心的),
right(正确的),wrong(错误的)
wise, clever, nice, kind, silly,
rude, wrong, right, foolish,
natural, stupid, bad, brave,
cruel, honest,naughty,wise,rude等.
例如:
It’s very kind of you to help me.(=You are very kind to help me.)你能帮助我,真好.
It's very kind of you to look after my cat.你能照看我的猫,真好.
It’s kind of you to say so.(=You are kind to say so)
It’s very rude of her to say such words.(=She is very rude to say such words.)她说这样的话,真粗鲁.
It’s foolish of him to go alone.(=He is foolish to go alone.)他单独出去太傻了.
It's very nice of you to help me. 你来帮助我,你真是太好了.
It’s clever of you to work out the maths problem. It's very kind of you to look after my cat.
你真聪明,解出了这道数学题.
It’s foolish of you to do that.
It’s wrong of the other children to make fun of you.

②“It’s+adj.+for+sb.+不定式”表示“做某事对某人来说怎么样”.常用于表示事物的特征特点,表示客观形式的形容词.若形容词是描述做的事情（即adj描述的是to do）,不是对不定式行为者的品格进行评价,用for sb.这类形容词有:
important(重要的),necessary(必要的),
difficult(困难的),easy(容易的),
hard(艰难的),dangerous(危险的),
safe(安全的),useful(有益的),
pleasant(舒适的),interesting(有趣的),
impossible(不可能的),
right(正确的) likely(可能的)等，
例如:
It’s not easy for them to learn a foreign language.(=To learn a foreign language is not easy for them.)
对于他们来说学好一门外语不容易.
It's very hard for him to study two languages(=To study two languages is very hard for him).
对他来说学两门外语是很难的.
It’s very important for students to listen to teachers carefully.(=To listen to teachers carefully is very important for students.)对于学生来说上课认真听老师讲课是非常重要的.
It’s necessary for us to get to school on time.(=To get to school on time is necessary for us.)
对于我们来说按时到校是非常必要的.
It’s important for her to come to the party.=It is important that she should come to the party.
对她来说来参加聚会很重要.
It’s very dangerous for children to cross the busy street.对孩子们来说,穿过繁忙的街道很危险.
It’s difficult for us to finish the work. 对我们来说,完成这项工作很困难.

希望能帮助到你，祝学习愉快！