That unsolved problem keeps him awake at night.

That unsolved case keeps him awake at night.

He is devoting himself to his work.

The process of name resolution is very important in computer networks.

I did my best for the exam.

No problem, I will do that job.

That proposal is completely unthinkable.

As a practical question, how are we going to fund this project?

This exam is a matter of life or death for me.

He is viewing that situation as a serious problem.