填空题
What kind of person is a color-blind person? He can't ______________________ all kinds of colors.
填空题
What kinds of colors can most color-blind people see? Yellow and _________________________________.
填空题
For those who are almost blind to all colors, what kinds of colors can they only see? They can only see _________________________________.
填空题
How many people are almost blind to all colors? There are ___________________________ people who are blind to all colors.
填空题
Why is it dangerous for a color-blind person to pass the traffic lights? Because they don't know they can not ________________________the real colors.