That information is completely unnecessary.

He thinks that war is a necessary evil.

Do you understand the necessity of this project?

No problem, I will do that job.

That proposal is completely unthinkable.

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

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.