Shadow

That day, I walked on the street, having a camera in my hand. All of you may know what I was doing. I was taking pictures, and trying to find interesting shadows. When I went by a tall building, I found that I had two shadows. Why? I looked around then I figured out the answer. There was a building full of glasses not far away. Because of the reflection of the glasses, I got the other shadow. Don’t understand? Open your physics book!