What is she doing?
She's serving drinks (serve drinks)
What is she doing?
She's making a cake (make a cake)
What is he doing?
He's cleaning the furniture (clean the furniture)
What is she doing?
She is sending invitations
What is she doing?
She's decorating the room (decorate the room)
What is he doing?
He's sweeping the floor (sweep the floor)
What are they doing?
They're going shopping (go shopping)
What is he doing?
He is putting out the food (put out the food)
What is he doing?
He's choosing the music (choose the music)
What is he doing?
He's selling/buying tickets. (sell tickets / buy tickets)
What is he doing?
He's blowing up balloons (blow up balloons)