题干

如图是“追风者”磁悬浮列车悬浮原理的示意图.该列车通过磁体之间的相互作用,悬浮在轨道上方,以提高运行速度,这里的相互作用是指(  )

A:异名磁极相互吸引

B:同名磁极相互吸引

C:异名磁极相互排斥

D:同名磁极相互排斥

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答案(点此获取答案解析)

A

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B

    I'm David. Long ago I came to the city near my hometown to find a job. I met all kinds of difficulties and I used up all my money soon.

    It was dark outside one day. I got on a bus quietly. Suddenly, a passenger cried in a loud voice, "someone has stolen my money!" I felt nervous, because his money was in my hand. Some people suggested the driver drive the bus to the police station, but some were against it because they were in a hurry to go back home. The whole bus was very noisy. The driver then stopped the bus by the roadside and turned on the lights. At that time, one passenger said, "Turn off the lights and give the thief(小简)a chance to take out the money."Then the bus got dark.

    When I was still thinking about whether to take out the money or not, the lights were turned on again. There was no money on the floor. Someone said, "Give him one more chance." Then the lights were turned off again. I became even more nervous. The lights were turned on again but they got the same result.

    Then the passengers fell into an open discussion. Later, someone said, "Give him the last chance!" I felt awakened(醒悟的) and took out all the money when the lights were turned off again.

    For many years I have been grateful to those who gave me three chances. When the first and Second chances come, you may not be prepared well or don't have enough courage to act. When the third chance comes, you should know clearly what you should do.

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