摘要：( ) If you are 13 years old, you . A. need to pay 49 yuan for your lunch at the Sunday Family Buffet B. can eat for free at the Sunday Family Buffet C. can’t buy one, get one free in Sports City Bar D. must go to Sports City Bar with your parents B About ten men in every hundred have the trouble of color blindness in some way. Women are luckier, only about one in two hundred is affected in this matter. Perhaps, after all, it is safer to be driven by a woman. There are different kinds of color blindness. For example, a man cannot see deep red. He may think that red, orange and yellow are all shades of green. Sometimes a person can’t tell the difference between blue and green. Only a few unlucky men may see everything in shades of green-a strange world indeed. Color blindness in human beings is a difficult thing to explain. In only one eye there are millions of very small things called “cones . These help us to see in the bright light and to tell differences between colors. There are also millions of “rods , but these are used for seeing when it is nearly dark. They show us shapes but not colors. Some insects have favorite colors. Mosquitoes like blue but do not like yellow. A red light will not attract insects, but a blue light will. Human beings also have favorite colors. Yet we are lucky. With the help of the cones in our eyes, we can see many beautiful colors by day, and with the help of the rods we can see shapes at night. Choose the best answer according to the passage.

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