It is +形容词 + of/for sb. + to do sth.
如果句型中的形容词用来形容人的,就用of,否则就用for.
例句：
It is necessary for us to drink plenty of water. necessary: 不是用来形容人的形容词.
It’s kind of you to help me.kind:用来形容人的形容词.
填空:
1.It is useful for me to learn a foreign language.

学一门外语对我来说是很有用的。
2.It is clever of the boy to do that.

那个男孩那样做很聪明。
3.It is not easy for her to do so much work in a day.

对她来说一天干这些活是很容易的。
4.It is imprtant for them to arrive on time.

对他们来说准时到达很重要。