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科学素养与生活应用·英语30篇(9)

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Why Traffic Lights Change Without a Person Watching

Why Traffic Lights Change Without a Person Watching

为什么交通灯无需人工值守就能自动变换

  1. Traffic lights use small computers called controllers inside their boxes.
  2. These controllers follow timed patterns set by city engineers.
  3. Some also sense cars with magnetic wires under the road.
  4. When a car stops above the wire, the light changes faster.
  5. Cameras and radar help newer systems respond to real traffic flow.
  6. Automation keeps traffic moving safely and smoothly.
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