It is no use telling him not to worry.为什么tell不加不定式啊

题目

It is no use telling him not to worry.为什么tell不加不定式啊

答案

It is no use doing sth 是一种固定结构,固定用法（干某事没有用处没有好处）,还有it's no good doing sth 等等doing 是动名词作真正的主语 而it is useful to do sth / it is important to do sth 等等,都是习惯用...