問題詳情：
When the traffic lights turn red, we will stop driving a car or crossing a street. Why is red used for traffic lights instead of other colors?
As we know, scattering(散*)happens when light goes through the air. For the same media(媒介), if the wavelength is long, the scattering will be short. If the wavelength is short, the scattering will be long.
Of all lights we can see red has the longest wavelength, so the scattering is the weakest. That means red travels far. In fact, it travels faster 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 lights help drivers stop in time and help prevent accidents.
1. When the traffic lights turn _____, we will stop driving a car.
A. red B. green C. yellow
2. According to the passage, the scattering of the red light is the _____.
A. longest B. weakest
C. farthest
3. The underlined word “wavelength” in Paragraph 2 means _____ in Chinese.
A. 波浪 B. 光波 C. 波長
4. What can the red light help drivers do?
A. It can help drivers in farther areas see the lights.
B. It helps drivers slow down or stop in time.
C. All of the above.
5. Which of the following is the best title?
A. Why do accidents happen?
B. How does the red light travel?
C. Why do we use red traffic lights?
【回答】
1. A。細節理解題。由第一段第一句可知。
2. B。細節理解題。由第三段第一句可知。
3. C。詞義猜測題。一方面, 根據length和long的拼寫形式相似可猜測length的詞義可能是“長度”；另一方面, 可以結合物理學知識猜測。
4. C。細節理解題。由最後一段可知。
5. C。主旨大意題。由第一段第二句可知。
知識點：說明文
題型：閱讀理解
