But the most natural thing of all would be to do nothing.
Now, it seemed the most natural thing in the world.
He let it out as the most natural thing one could say.
They were the most natural thing in the world to him.
It was the most natural thing in the world to do.
It had seemed the most natural thing in the world for them to be together.
You are learning to do the most natural thing in the world.
That feeling seemed to me the most natural thing in the world.
It may seem to you the most natural thing in the world.
All as though it were the most natural thing in the world.