He is researching about a new energy source.

He is conducting research on a new energy source.

Olfactory cells play an important role in allowing us to sense smells.

This cell is dividing very actively.

This fort was built to protect the town from enemies during wartime.

We should learn about disaster prevention.

He was immersed in the memories of his deceased wife.

The Chief Cabinet Secretary holds a press conference every day.

I caught a cold.

That news is a big topic in society.