Can you answer this question?

He received the letter challenging him to a duel and began preparing for the duel.

His role is to fulfill his responsibilities as a leader.

Gender roles are an important element in defining individual behavior in society.

It is important to understand the importance of health.

My town council is actively addressing local issues.

That unsolved problem keeps him awake at night.

That unsolved case keeps him awake at night.

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

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