it is+ adj.+ for sb to do还是it is+ adj.+

Answer 1

用for 是因为前面的adj是来描述do后面的sth.
用of 的话,adj就用来形容sb的
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,
it is adj for sb to do就是普通的形容词,如hard,impossible,important
翻译：对我们来说学习英语太难了

it is+adj+for sb to do...
it is+adj+of sb to do ....的含义及区别
一.导入
It is kind of you to help me.你能帮我太好了.（kind 形容的是you）
It is beneficial for you to do sports.运动对你有益.（beneficial形容的是do sports）
二.表达含义:
1.it is+adj+for sb. 就是“做…对某人(for sb)来说怎么样(adj)”
2.it is+adj+of sb. 就是“某人做…(of sb)怎么样(adj)”
三.辨析:it is+adj+for sb和it is+adj+of sb.
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.
③注意:for 与of 的辨别方法:
I.区别:
1.含义上的区别:
两种句型的主谓关系不一样.
It is+adj+for sb to do. adj应该是对做这件事的评价;
It is+adj+of sb to do sth. adj应该是对做这件事的人的评价,adj多用形容人的.
①It is +adj+for sb to do sth. 形容词(for前的)是多用来形容一件事情(动词不定式所表示的动作),
即修饰的是 to do sth. adj是do sth.的属性; sb.跟adj.没有直接联系. for是指干谋事会如何.
It's plesant for us to take a walk after supper.
②It is+adj+of sb to do sth. 形容词(of前的)是多用来形容人的;修饰的是介词of后面接的宾语. sb.跟adj.
有直接联系.
③实例辨析:
It's very difficult for me to do it. (difficult 指事情很难)
It's very kind of you to do it for me. (kind指人的品质好)
It is more convenient for him to walk directly.对他来说,直接走过来比较便捷. (convenient 指事情很便捷)
It is clever of him to come down without ropes.他很聪明,不用绳子就能下来. (convenient 指指人很聪明)
2.逻辑结构上的区别:
方法:取介词of/for后的代词作逻辑主语和介词前边的形容词作表语,造个句子.
句子结构:“逻辑主语+be+形容词”.即:sb.is adj to do sth (不定式作句子的状语).
如果道理上通顺用of,不通则用for.如:
It is good for you to look at this book. 是说: ....对你有好处. 看这本书对你有好处.
It is nice of you to give me such advice.是说: 你很好,感激你给我提供建议.
*提取逻辑主语和形容词造句:
It is nice of you to help me. 提取you与nice 可构成you are nice. (通顺,所以应用of).
It's very kind of you to help me. 提取you与kind可构成you are kind. (通顺,所以应用of).
It is good for you to look at this book.提取you与good可构成you are good(有好处的). (不通,所以应用for)
It is hard for him to study two languages. 提取he与hard可构成he is hard(困难的). (不通,所以应用for)
四.注意:
of sb. 的句型通常都可转换为不定式作状语的句子,但for sb.句型不可以.
It’s very nice of you to offer me a seat.
= You are nice to offer me a seat. 十分感谢你给我让座.
It is careless of him to lose so many things.
= He is careless to lose so many things. 他丢了这么多东西,真是太粗心了.
It’s very important for you to practise your oral English in daily life.