His actions show genuine friendship.

The coastline is gradually changing its shape due to the erosion by waves.

The coastline has changed shape due to years of erosion.

He is proud to be a subject of the emperor.

The astronomers began observing the nova.

This experiment is conducted in a vacuum.

I went to the department store to buy new bedding.

The city becomes quiet when it's midnight.

He is majoring in psychology.

It's difficult to understand his mental state.