If we are driving a car or crossing a street, we will stop when the traffic lights turn re

If we are driving a car or crossing a street, we will stop when the traffic lights turn red. Why do we use red rather than other colors?
As we know, scattering (散射) happens when light goes through the air. For the same media, if the wavelength (波长) is long, the scattering will be short. If the wavelength is short, then the scattering will be long.
Of all light we can see red has the longest wavelength, so the scattering is the weakest. That means the red light travels far. In fact, it travels farther on rainy days.
Using the red light can help drivers in farther areas see the lights. It helps drivers slow down or stop in time. If drivers don’t see the red light until they are close, they may not be able to stop the car in time. An accident may happen. Red can also excite people. We can act more quickly when we see the color red.
In a word, red light helps drivers stop in time and help prevent accidents.
【小题1】     has the longest wavelength of all light we can see.A．RedB．GreenC．YellowD．Black【小题2】Red light travels farther on      days.A．windyB．sunnyC．rainyD．cloudy【小题3】Red can make people act more quickly because     .A．red can make people happierB．the scattering of red is very shortC．the scattering of red is very longD．red can make people more excited【小题4】The underlined word “prevent” means      in Chinese.A．逃避B．防止C．处理D．检查【小题5】The passage mainly tells us     .A．why accidents happenB．how the red light travelsC．why we use red traffic lightsD．how to stop in time at traffic lightsA