He is feigning ignorance about that problem.

He knows that pain through his own experience.

I have no way of knowing what he is thinking.

He is working hard to make his abilities known to the world.

In order to understand his feelings, I had a deep conversation with him.

God only knows what he is thinking.

He works at a non-governmental organization.

She described the pain of a broken heart as tears.

I don't know a thing about him.

He emphasized his belief by saying, 'I believe in order to understand.'