They are my best friends.

His existence enriches my life.

You can feel his presence.

This problem is very serious.

Do you understand the seriousness of this problem?

He and she were standing against each other due to a disagreement.

There is a serious opposition between them.

During summer vacation, I will go to the beach.

While he was taking a nap, I finished my homework.

He took a little pause before speaking.