Ventilators are provided in rooms just below the roof . Why?

Room are provided with the ventilators near the roof. Why?

Statement-1: Ventilators are provided at the top of the room. Statement-2: Their purpose is to bring oxygen for breathing.

Statement-1: Ventilators are provided at the top of the room. Statement-2: Their purpose is to bring oxygen for breathing.

Why does the ventilators provided near the ceilling of class room?

Why spokes are provided in a bicycle wheel ?

Why spokes are provided in a bicycle wheel?