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如图所示,两块竖直放置的金属板间距为d,用导线与一匝数为n的线圈连接.线圈内部分布有方向水平向左的匀强磁场.两板间有一个一定质量、电荷量为+q的油滴在与水平方向成30°角斜向右上方的恒力F的作用下恰好处于平衡状态.则线圈内磁场的变化情况和磁通量的变化率分别是(  )
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B

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    Many years ago, my dad was facing a serious heart condition. He was1 to do a(n) steady (稳定的) job. Sometimes he fell suddenly ill and had to be 2 to the hospital.

    He wanted to do something to keep himself busy, so he 3to volunteer at the local children's hospital. My dad loved kids. It was the perfect 4 for him. He ended up working with the 5 children. He would talk, play, and do arts with them.

    One of his 6 was a girl with a 7 that paralyzed (使瘫痪) her from the neck down. She couldn't do anything, and she was very 8My dad decided to try to 9 her. He started visiting her in her room,10 paints, brushes and paper. He 11the paper up, put the paintbrush in his mouth and began to12 He didn't use his hands at all. All the while, he would tell her, “See, you can do anything you set your 13to.”

    At the end of the day, she began to paint using her 14 and she and my dad became friends. Soon after, the little girl was sent 15because the doctors felt there was nothing else they could do for her. My dad also 16 the children's hospital for a little while because he became ill. Some time later, after my dad had 17 and returned to work, the little girl who had been paralyzed came in, but this time she was18She ran straight over to my dad and hugged him really tight. She gave him a 19she had done using her hands. At the bottom it 20“Thank you for helping me walk.”

    My dad said sometimes love is more powerful than the doctor.