题干

如图所示,放在水平地面上的光滑绝缘圆筒内有两个带正电小球ABA位于筒底靠在左侧壁处,B在右侧筒壁上受到A的斥力作用处于静止.若A的电量保持不变,B由于漏电而下降少许重新平衡,下列说法中正确的是( )

A:小球A对筒底的压力变小

B:小球B对筒壁的压力变大

C:小球AB间的库仑力变小

D:小球AB间的电势能减小

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B

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    I’m seventeen. I had worked as a box boy at a supermarket in Los Angeles. People came to the counter and you put things in their bags for them and carried things to their cars. It was hard work.

    While working, you wear a plate with your name on it. I once met someone I knew years ago. I remembered his name and said, "Mr. Castle, how are you?" We talked about this and that. As he left, he said, "It was nice talking to you, Brett." I felt great, he remembered me. Then I looked down at my name plate. Oh, no. He didn’t remember me at all. He just read the name plate. I wish I had put "Irving" down on my name plate. If he’d have said, "Oh yes, Irving, how could I forget you?" I’d have been ready for him. There’s nothing personal here.

    The manager and everyone else who were a step above the box boys often shouted orders. One of these was: you couldn’t accept tips. Okay, I’m outside and I put the bags in the car. For a lot of people, the natural reaction is to take a quarter and give it to me. I’d say, "I’m sorry, I can’t." They’d get angry. When you give someone a tip, you’re sort of being polite. You take a quarter and you put it in their hand and you expect them to say, "Oh, thanks a lot." When you say, "I’m sorry, I can’t." they feel a little put down. They say, "No one will know." And they put it in your pocket. You say, "I really can’t."

    It gets to a point where you almost have to hurt a person physically to prevent him from tipping you. It was not in agreement with the store’s belief in being friendly. Accepting tips was a friendly thing and made the customer feel good. I just couldn’t understand the strangeness of some people’s ideas. One lady actually put it in my pocket, got in the car, and drove away. I would have had to throw the quarter at her or eaten it or something.

    I had decided that one year was enough. Some people needed the job to stay alive and fed. I guess I had the means and could afford to hate it and give it up.