用of 的话,adj就用来形容sb的.即形容词是描述不定式行为者的性格、品质的,如kind,good,nice,right,wrong,clever,careless,polite,foolish等,用of sb..故可以换成sb is adj to do
比如：it‘s nice of you to help me.=you are nice to help me.
1 It’svery kind of you to help me. 你能帮我,真好.
2 It’s clever of you to work out the maths problem. 你真聪明,解出了这道数学题.
用for是因为前面的adj是来描述do后面的sth.即形容词仅仅是描述事物,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difficult,easy,hard,important,dangerous,（im）possible等.如
1 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.

2It’s difficult for us to finish the work. 对我们来说,完成这项工作很困难.
祝你假期愉快!加油!不明白再问!如果帮到你,请采纳,谢谢!请问这道题……It's very nice ___ pictures for me.A. of you to draw B. for you to draw C. for you drawing D. of you drawingA翻译……你给我画画，你真好。