4.From the
experiment we can conclude that about _____ of people who suffered from heart
attacks without aspirin died.
A. 7% B. 11% C. 19% D. 44%
Passage 24
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, L on
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’ll 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.