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

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．Red B．Green C．Yellow D．Black 小题2:Red light travels farther on ______ days.
A．windy B．sunny C．rainy D．cloudy 小题3:Red can make people act more quickly because ____________.
A．red can make people happier B．the scattering of red is very short
C．the scattering of red is very long D．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 happen B．how the red light travels
C．why we use red traffic lights D．how to stop in time at traffic lights

小题1:A
小题1:C
小题1:D
小题1:B
小题1:C



小题1:根据we can see red has the longest wavelength,描述可知选A。
小题1:根据In fact, it travels farther on rainy days. 可知选C。
小题1:根据Red can also excite people. We can act more quickly when we see the color red. 可知选D。
小题1:根据上文stop in time 及时停止，可知下文句意为预防阻止事故，故选B。
小题1:通过短文描述可知本文主要是介绍了人们为什么使用红色作为交通信号灯，故选C。

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