题干

条形磁铁竖直放置,闭合圆环水平放置,条形磁铁中心线穿过圆环中心,如图所示,若圆环为弹性环,其形状由Ⅰ扩大到Ⅱ,那么圆环内磁通量的变化的情况是 (      )

A:磁通量增大

B:磁通量减小

C:磁通量不变

D:条件不足,无法确定

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答案(点此获取答案解析)

B

同类题5

阅读下面短文,从短文后的五个选项中选出能填入空白处的最佳选项。每个选项只能用一次。

    Is there anything worse than that? You bravely raise your hand to answer a question, but your teacher just point out that you’re wrong. What a shame! What could the teacher make you suffer (忍受) this?

    Relax. ____. Your teacher isn't calling you out to humiliate (使丢脸) you, but rather out of concern for you and your education.

    Having all your classmates come to know your weak points can be pretty hard, so how can you get past the shame and recognize class participation as a learning opportunity?

    Get out of your comfort zone. Terrill Schumaker, a teacher, explains that “the more you speak out, the more you learn how to grow and build confidence. ____

    Realize it's not a big deal. ____. People aren’t going to care all that much. “If I'm wrong or make a stupid point, then people laugh at me, but life moves on” says Grade 12 Kristen Wesenberg. Besides, everybody makes mistakes, and you can't be perfect all the time.

    ____. Of course it takes courage (勇气), but as Wesenberg says, ―What's the point of living in fear?‖ You won't learn anything if you are not brave enough.

    Use the experience as a learning tool. Wesenberg advises asking teachers why you're wrong so they can explain and you can learn.____. If you're wrong now, at least you won't be wrong in your next test!

A. Be brave in class

B. Trust your teacher instead

C. Use class time as a mini—test

D. And it's not the end of the world

E. Then you can live an exciting life