阅读理解

Passage 2

Questions 16—20 are based on the following passage.

Traffic lights, or traffic signals, are located on most major corners in cities and townsaround the world. The red, yellow and green lights let us know when it is safe to drive throughthe intersection(十字路口)and when to walk across the street as well as when to stop and letother drivers, bikers and pedestrians take their turns to continue on their way.

Traffic jams were a problem even before the invention of the automobile. Horse-drawncarriages and pedestrians crowded the roads of London in the 1860s. A British railway manager,John Peake Knight, suggested adapting a railroad method for controlling traffic.

Railroads used a semaphore(信号)system with small arms extending from a pole to indicatewhether a train could pass or not. In Knight's adaptation, semaphores would signal“stop"and"go"during the day, and at night red and green lights would be used. Gas lamps would light upthe sign at night. A police officer would be stationed next to the signals to operate them.

The world's first traffic signal was installed on Dec. 9, 1868, at the intersection of BridgeStreet and Great George Street in the London borough of Westminster, near the Houses ofParliament and the Westminster Bridge. It was a success and Knight predicted more would beinstalled.

However, only one month later, a police officer controlling the signal was badly injuredwhen a leak in a gas main caused one of the lights to explode in his face. The project was declareda public health hazard and immediately dropped.

Following the accident, about four decades passed before traffic sighnals began to grow inpopularity again, mainly in the United States as more automobiles hit the road. The early 1900ssaw several patents being field, each with a different innovation to the basic idea.

The first electric traffic light using red and green. lights was invented in 1912 by LesterFarnsworth Wire, a police officer in Salt Lake City, Utah. Wire's traffic signal resembled a four-sided bird-house mounted on a tall pole. It was placed in the middle of an intersection and waspowered by overhead trolley wires. A police officer had to manually switch the direction of thelights.

【正确答案】 C

【答案解析】推理判断题。根据第一段第二句The red,yellow and green lights let us know when it issafe to drive through the intersection and whento walk across the street as well as when to stopand let other drivers, bikers and pedestrians taketheir turns to continue on their way(红色、黄色和绿色的灯让我们知道什么时候可以安全地过十字路口、什么时候可以过马路及什么时候可以停车，让其他司机、骑自行车的人和行人轮流继续前行)可知，交通信号灯的好处是帮助解决交通堵塞。故选C。