What sport is this?
baseball
What is he doing?
He is playing the guitar.
What sport is this?
badminton
What is he doing?
He is riding a bike.
What is she doing?
She is playing tennis.
This is...
sport (sports)
What is she doing?
She is playing basketball.
What is she doing?
She is playing the piano.
What are they doing?
They are watching television.
What is she doing?
She is swimming.
What is he doing?
He is playing football.