It seems to be strange to you there is a blind spot(盲点)on the eyes, Here is an interesting experiment(实验)that can make something disappear, when one eye is open. Make a card about the size of a postcard and write two English letters L and R on it, Lon the left and R on the right. First, hold the card about 80 cm away and you see both the letters. Then close your right eye and look at the letter R only with your left eye. And now, as you move the card slowly towards you, you' 11 find the letter L disappearing. But if you move the card nearer to your face, the letter will be seen again. Now do the same experiment with your left eye closed, you'll find the letter R disappearing. Why does the letter disappear? It is because there is a blind spot on the eye. When the image（影像）of the letter falls on the blind spot, it won't be seen. That is why either of the letters disappears． 小题1:The writer of the passage thinks that_______ there is a blind spot on the eye.
①Hold the card ②Move the card nearer ③Close your right eye ④write two English letters ⑤Look at the letter R ⑥Make a card
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