Although he was tired, he continued to work.

Despite my opinion, he pushed through with his own thoughts.

This problem is very complex and cannot be solved easily.

The structure of this building is very complex.

He is a person who cares about every detail.

He has no involvement in the incident at all.

His actions have a deep connection to all of us.

He is always concerned about his health.

His actions are a matter of concern to all of us.

I became deeply involved in his problem.