Doorbell
Doorbells make a sound when people push them.
The sound lets tenants know that someone is at the door.
The man is ringing the doorbell to Apartment 105-F.
Elevator
Some apartment buildings have elevators.
Elevators carry people up to higher floors and down to lower floors.
The woman is pushing the button for the elevator because she doesn't want to walk up the stairs.
Staircase
A staircase is a set of stairs.
Stairs are also called steps.
Two boys are sitting on the staircase. They are talking.