学进去

About ten men in every hundred suffer from color blindness in some way. W1． are luckier. Only about one in two hundred is affected in this matter. Perhaps, after all, it’s s2． to be driven by a lady.

There are different forms of color blindness. In some cases, a man cannot see deep red. He may think that red, orange and yellow are all shades of green. In rare cases, an unlucky man may see e3． in shades of green.

Color blindness in human beings is a strange thing to e4．. In a single eye, there are millions of very s5． things called “cones（视锥细胞）”. These help us to see in a bright light and to tell the difference between colors. There are also millions of rods（视杆细胞）but these are used for seeing when it is n6． dark. They show us shape but no color.

Some insects have favorite colors. Mosquitoes like blue but do not like yellow. A red light will not attract insects, but a blue lamp will. In a similar way, 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, a7． with the help of the rods, we can see shapes at night. One day we may even learn more about invisible colors around.