题干

在地球上做这样的实验:一人在一根较长的空心钢管的一端敲击一下,另一人在钢管的另一端耳朵贴近管口会听到两次声音.两次响声的时间间隔一定大于____ s以上;后一次听到的响声是经____传来的,其理由是____.若在月球上做同样的实验,另一端的人会听到____次声音.原因是____
上一题 下一题 0.0难度 选择题 更新时间:2017-08-28 12:05:36

答案(点此获取答案解析)

0.1,空气,空气中的声速小于钢铁中的声速,1,真空不能传声

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    It started as a special day for Wesley Autrey, a 50-year-old construction worker in New York City. It was about 12:45 P.M., and he was waiting on a subway platform (月台) to take his daughters home before he went to work. He suddenly noticed a man nearby have convulsions (抽搐) and fall down suddenly. Mr. Autrey and two women went to help the stranger. The man, Cameron Hollopeter, managed to get to his feet, but then stumbled (绊倒) at the edge of the platform and fell onto the subway tracks. Mr. Autrey looked up and saw the lights of the subway train coming near through the tunnel.

    Mr. Autrey jumped onto the track immediately. He realized that he didn't have time to get Mr. Hollopeter and himself back up on the platform before the train arrived, so he lay on top of the man and pressed down as hard as he could. Although the driver tried to stop the train before it reached them, he couldn't. Five cars passed over them before the train finally stopped. The cars had passed only inches from his head.

    New York loves a hero. Mr. Autrey became an overnight hero and was named the “Subway Superman”. New York City Mayor Michael Bloomberg gave him the Bronze Medallion, the city's highest honor. He was asked to appear on several TV talk shows. He was also rewarded with money and gifts, such as $10,000 from Donald Trump, a $5,000 gift card from the Gap clothing store, a new Jeep, and Beyonce concert tickets.

    How did Autrey react (反应) to all this? He said, “I don't feel like I did anything great; I just saw someone who needed help. I did what I felt was right”.