Are they cleaning the house?
yes, they are cleaning the house.
Is she playing guitar?
No, she isn't playing guitar.
Is he studying?
Yes, he is studying
Is she walking?
No, she isn't walking.
What is he doing?
He is reading a book.
What are they doing?
They are talking.
What is he doing?
He is watching youtube
What is she doing?
She is running
What is he doing?
He is drinking coffee.