Question

    When we were little kids, we knew about traffic lights. The color red means stop, the color green means go and the color yellow means slow down or show some caution (小心). But why are these colors used for traffic lights? Why couldn't they be colors like blue, brown or orange? Here is the history of the colors for traffic lights.

Well, it's important to know that before there were traffic lights for cars, there were traffic signals (信号) for trains. At first, railway companies used red to mean stop, white to mean go and green to mean caution. But train drivers had a few problems with the color white meaning go. They could easily mistake stars at night for the signal to go. So railway companies moved to the color green to mean go, and the color yellow to mean caution.

The color red has a lot to do with danger. Red is the color with the longest wavelength (波长), so it can be seen from a greater distance than other colors. The color yellow is used to mean caution because it has a little shorter wavelength than red, but not as short as green.

Believe it or not, yellow was once used to mean stop. Back in the 1900s, some stop signs were yellow because they were easier to see in poorly-lit areas. But people once again used red to mean stop after more highly reflective (反光) materials were developed. Since yellow can be seen well at all times of the day, school zones and school buses continue to be painted yellow.

Traffic lights really came a long way.

From: https: //www.rd.com

1.The earliest traffic signals were for trains.

2.The color blue was once in early traffic signals.

3.The color green can be seen from a greater distance than other colors.

4.Back in the 1900s, yellow was used to mean stop.

5.School buses are painted yellow because this color can be seen at all times of the day.

Answer

1.A

2.B

3.B

4.A

5.A

【解析】

文章主要是介绍交通灯颜色的历史。。

1.

细节理解题。根据文中At first, railway companies used red to mean stop, white to mean go and green to mean caution.可知，起初交通灯是为火车准备的，所以这里的描述是正确的，故填A。

2.

细节理解题。根据文中When we were little kids, we knew about traffic lights. The color red means stop, the color green means go and the color yellow means slow down or show some caution (小心). But why are these colors used for traffic lights? Why couldn’t they be colors like blue, brown or orange? Here is the history of the colors for traffic lights.可知，蓝色没有被作为交通灯而使用，故填B。

3.

细节理解题。根据文中Red is the color with the longest wavelength (波长), so it can be seen from a greater distance than other colors. The color yellow is used to mean caution because it has a little shorter wavelength than red, but not as short as green.可知，是红色比其他颜色从很远的地方可以看到。所以这里的描述是错误的，故填B。

4.

细节理解题。根据文中Back in the 1900s, some stop signs were yellow because they were easier to see in poorly-lit areas.可知，早在20世纪，黄色就被用来表示停止。所以这里的描述是正确的，故填A。

5.

细节理解题。根据文中Since yellow can be seen well at all times of the day, school zones and school buses continue to be painted yellow.可知，由于一天中任何时候都能很好地看到黄色，学校区域和校车继续被涂成黄色。所以这里的描述是正确的，故填A。