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.

Red is the color of China. Among all the colors, red is most   16 seen. The color red is fresh and pure, and in China we call it China Red. Chinese people are attracted by the color red not only because it makes people excited, but also because it has   17  meaning in Chinese culture and history.
No country in the world has ever   18  a color in such a way as China. Here, red is a symbol. It gives color to the soul (灵魂) of the nation. In the past, red represented dignity (尊严) and mystery. Even now, Chinese people   19  the color much more than the rest of the world does. It can be said that China Red is an everlasting theme for China, and an important color for the Chinese people. China Red has   20  a very popular phrase, attracting the world’s attention.
Finding red-colored things in China is very   21 , as you can see the color everywhere. All traditional red things have played special roles in China. Things like the walls of ancient palaces, the   22  flag, Chinese knots, lanterns, traditional paper-cuts, and even tanghulu are all red.
Red is the color of   23 , health, harmony, happiness, peace, wealth and so on. Only real things and events can fully   24  red’s real beauty. The color can be alive and breathing only when it’s connected with people.
In China, red is more than just a color. It carries the ancient history and   25  of the Chinese nation. China Red is filled with mysterious charm beyond description and it is right here in China waiting for you to feel and discover!