I will take a flight in economy class.

She always carries a self-defense spray with her.

They (referring to women or girls) are my best friends.

He solved the problem using that technique.

He is learning the art of painting.

He defeated the enemy using that technique.

He specializes in the study of fish claspers.

Long-haul flights increase the risk of economy class syndrome.

You must be careful of economy class syndrome on long flights.

He is known as an expert in the practice of law.