My friend was diagnosed with keratoconus.

He is learning the art of painting.

He solved the problem using that technique.

He defeated the enemy using that technique.

Oh, if that's the case, it's fine.

He started running to chase the criminal.

He is a person who can make an appropriate response in any situation.

He always takes an arrogant attitude.

I can't stand his arrogant attitude.

He is studying about the ancient royal family.