What is the difference between “ in” and “ about”？

For instance：
She was not lacking in/about courage.

Thank you. ~

Question

What is the difference between “ in” and “ about”？

For instance：
  She was not lacking in/about courage.

Thank you. ~

Answer

The expression is "lacking in", so the version with "about" is simply wrong.

Answer

Literally, "about" means in the area of something or near it. So "in" works here, but "about" does not.

Answer

It depends on the object. The preposition determines the place of the object. Courage would be in, not about, the person.