Question

为什么It feels good to be able to 与It feels good being able to.

为什么不能用being代替to be?

It feels good to be able to meet a need like that.
It feels good being able to meet a need like that.

Answer 1

这里是it作形式主语指代后面的动词不定式,等同于To be able to ...feels good.就是一种固定的用法,现在分词无此用法.

Answer 2

it是形式主语。后面的不定式是真正的主语。这是固定的语法。

Answer 3

feel good 后面用不定式继续陈述事情，表目的。