A、Bridge-building experts. B、Washington Roebling. C、John Roebling. D、The Roeblings. C录音讲到1883年，a creative engineer John Roebling

The Brooklyn Bridge is simply an engineering miracle. In 1883, a creative engineer John Roebling was inspired by an idea for this spectacular bridge project. However, bridge-building experts told him to forget it. It just was not possible. Roebling convinced his son Washington, an up-and-coming engineer, that the bridge could be built. The two of them conceived the concept of how it could be accomplished, and how to overcome the obstacles. Somehow they convinced bankers to finance the project. Then with excitement and energy, they hired their crew and began to build their dream bridge.
    The project was only a few months under way when a tragic on-site accident killed John Roebling and severely injured his son. Washington was severely brain-damaged, unable to talk or walk. Everyone thought that the project would have to be dropped since the Roeblings were the only ones who understood how the bridge could be built.
    Though Washington Roebling was unable to move or talk, his mind was as sharp as ever. One day, as he lay in his hospital bed, an idea flashed in his mind as to how to develop a communication code. All he could move was one finger, so he touched the arm of his wife with that finger. He tapped out the code to communicate to her what she was to tell the engineers who continued building the bridge. For 13 years, Washington tapped out his instructions with one finger until the spectacular Brooklyn Bridge was finally completed.
Question 16-20 are based on the passage you’ve just heard:
16. Who came up with the idea of building Brooklyn Bridge?
17. What do we learn about the project?
18. What happened to the son after the construction began?
19. What part of Washington Roebling remained intact after the accident？
20. Why is the Brooklyn Bridge regarded as an engineering miracle?