He was reading a book to kill time.

Looking at it overall, I think this project is a success.

What on earth is happening?

A totalitarian political system deprives individuals of their freedom.

Do you understand the necessity of this project?

That information is unnecessary.

That information is completely unnecessary.

He thinks that war is a necessary evil.

That unsolved problem keeps him awake at night.

That unsolved case keeps him awake at night.