A Blind Spot

摘要

It seems to be strange to you there is ablind spot on the eye. Here is an interestingexperiment (实验)that can make somethingdisappear,when one eye is open. Make a card about the size of a postcardand write two English letters L and Ron it.L on the left and R on the right.First,hold the card about 80cm away and you seeboth the letters.Then close your right eye