proper way to reversing the car is use its rear window not side mirrors

Who taught you this way of reversing a vehicle ? One would fail in a driving test if doing so.
Scroll up and read --I didn't say anything regarding rear or side mirrors.I wrote mirrors only.
You are 100% right. All three mirrors are actually needed. I personally feel handicapped if any of the mirrors is not there due to any reason. I wonder how people fold the side view mirrors and keep driving even reversing the cars.
so my driving test is coming up pretty soon, and I would like to get some advice from ppl who have taken that driving test recently.
Always stop at zebra crossing when pedestrians are using it. On zebra crossing, pedestrian have right of way.
When joining a main road from a sub road (taking a left turn), always slow down and look to right and stop if you think someone coming from right side will have to break due to you joining the main road.
When confused about right of way, the vehicle on your right has always the right of way. He must go first and then you should.
Don't use horn unless someone is violating. Using horn to make your way is illegal.
Never use horn to alert old people, you should stop and let them pass first. If really necessary, accelerate your engine few times or use horn for a fraction of a second only so that they get alert of approaching vehicle. (This may not be a traffic rule but would feel like an honor to anyone)
In a round about, the vehicles already in round about have right of way. You should not enter if there is a vehicle coming in round about from your right hand side.
Sometimes the driving test examiners silently watch what you are doing, so follow these rules not only during the test but for the rest of your life.
All the best.....