题目

Look into the mirror and what do you see? You see yourself. But when you move. you do everything backward(相反地)in the mirror! If you wave your left hand, your right hand waves in the mirror. If you wink your right eye, your left eye, your left eye winks(眨). Try to read a page in the mirror .The words will be backwards.What is really happening? You do not see through the glass of a mirror as you do through a window. The glass of a mirror has a silver coating on the back. The light from the sun or a bulb bounces (弹回)off you ,goes into the mirror ,and bounces straight back out to you a已知二次函数f（x）的图象如右上图所示，则其导函数f′（x）的图象大致形状是（ ）A．B．C．D．