怎样区分It is+形容词+of sb to do sth 和It is+形容词+for sb to do sth

It is+形容词+of sb to do sth 是形容人的品质的,例如,It's kind of you to help me.It's nice of you to help me.而It is+形容词+for sb to do sth则是形容事物的性质的,例如,It impossible for me to finish the j...