Hospitals before and after each door front door to the front door of the people come to the red light on the bell ringing back door to the people come to the green light on the bell ringing please des

According to the question, the red light at the front door and the green light at the back door can work alone, so they are connected in parallel,

and there is a switch to control each of them, but no matter which switch is closed, the bell rings, so the bell is on the dry circuit,

The circuit diagram is as shown in the figure:

So the answer is: the circuit diagram as shown in the figure.

The answer is: The circuit is shown in the figure.