That unsolved case keeps him awake at night.

He is devoting himself to his work.

She was devastated by sadness and cried her eyes out all night.

I did my best for the exam.

He used every possible means to make the project successful.

A new approach is needed to solve this set of problems.

The main problem with this project is the lack of communication.

This question text is too difficult, it's hard to understand.

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

He is viewing that situation as a serious problem.