不定式作定语,一般情况下有四种情况：
1.与被修饰词之间存在逻辑主谓关系：He was the last parent to leave.
2.与被修饰词之间存在逻辑动宾关系：Do you have anything to deal with/to be dealt with
3.在泛指名词place/way/reason/time/right等词之后：You have no right to blame me.
4.可以跟to do 的动词、形容词如able,hope,need等的名词形式ability,hope,need可以直接用不定时作定语：There is no need to discuss it.
这里属于第二种咯