What is the category of this land?

Kubo is my best friend.

The theory of spacetime is an important part of physics.

Souroku is my best friend.

Mr. Shimokubo is my best friend.

He is a reticent person, so he doesn't talk much.

He is a reticent person, so he doesn't talk much.

He belonged to an ancient clan.

The closing ceremony of the Olympics was moving.

When fluid accumulates in the pleural cavity, it becomes difficult to breathe.