A little boy is sitting down reading a book.
A child is looking at a book.
A kid is playing on a swingset outdoors.
Bill Gates and Steve Ballmer are billionaires.
She has to go across town after her appointment.
it is certainly
A man is cleaning the floor.
The people were sitting on the ground.
I think it's time to make the process more complicated and you probably won't understand even after I explain why.