问题 选择题

如图所示中,L1和L2是两个相同灯泡,L是一个自感系数相当大的线圈,其电阻值与R相同,在开关S接通的瞬间,下列说法正确的是(  )

A.接通时L1先达到最亮,断开时L1后灭

B.接通时L2先达到最亮,断开时L2后灭

C.接通时L1先达到最亮,断开时L1先灭

D.接通时L2先达到最亮,断开时L2先灭

答案

接通时由于L自感作用,瞬间等于断路,通过L1的电流等于L2+R之和,所以L1先达到最亮.然后L自感慢慢减弱,通过L1的电流减小,然后熄灭;

当断开时,L2瞬间失去电流,而L1和L构成回路,由于L自感,L1会亮一会再灭,故A正确BCD错误.

故选:A

判断题
阅读理解

第三部分阅读理解 (共15小题;每小题2分,满分30分)

请认真阅读下列短文,从短文后各题所给的A、B、C、D四个选项中,选出最佳选项,并在答题卡上将该项涂黑。

A

Why You Should Celebrate Your Mistakes

When you make a mistake, big or small, cherish (珍视) it like it’s the most precious thing in the world. Because in some ways, it is.

Most of us feel bad when we make mistakes, beat ourselves up about it, feel like failures, get mad at ourselves.

And that’s only natural: most of us have been taught from a young age that mistakes are bad, that we should try to avoid mistakes. We’ve been scolded when we make mistakes—at home, school and work. Maybe not always, but probably enough times to make feeling bad about mistakes an unconscious reaction.

Yet without mistakes, we could not learn or grow. If you think about it that way, mistakes should be cherished and celebrated for being one of the most amazing things in the world: they make learning possible; they make growth and improvement possible.

By trial and error—trying things, making mistakes, and learning from those mistakes—we have figured out how to make electric light, to paint the ceiling of the Sistine Chapel, to fly.

Mistakes make walking possible for the smallest toddler, make speech possible, make works of genius possible.

Think about how we learn: we don’t just consume information about something and instantly know it or know how to do it. You don’t just read about painting, or writing, or computer programming, or baking, or playing the piano, and know how to do them right away. Instead, you get information about something, from reading or from another person or from observing usually … then you construct a model in your mind … then you test it out by trying it in the real world … then you make mistakes … then you revise the model based on the results of your real-world experimentation … and repeat, making mistakes, learning from those mistakes, until you’ve pretty much learned how to do something. That’s how we learn as babies and toddlers, and how we learn as adults. Mistakes are how we learn to do something new—because if you succeed at something, it’s probably something you already knew how to do. You haven’t really grown much from that success—at most it’s the last step on your journey, not the whole journey. Most of the journey was made up of mistakes, if it’s a good journey.

So if you value learning, if you value growing and improving, then you should value mistakes. They are amazing things that make a world of brilliance possible.

56. Why do most of us feel bad about making mistakes?

A. Because mistakes make us suffer a lot.

B. Because it’s a natural part in our life.

C. Because we’ve been taught so from a young age.

D. Because mistakes have ruined many people’s careers.

57. According to the passage, what is the right attitude to mistakes?

A. We should try to avoid making mistakes.

B. We should owe great inventions mainly to mistakes.

C. We should treat mistakes as good chances to learn.

D. We should make feeling bad about mistakes an unconscious reaction.

58. The underlined word “toddler” in Paragraph Six probably means _______.

A. a small child learning to walk             B. a kindergarten child learning to draw

C. a primary pupil learning to read                     D. a school teenager learning to write

59. We can learn from the passage that _______.

A. most of us can really grow from success

B. growing and improving are based on mistakes

C. mistakes are the most precious things in the world 

D. we read about something and know how to do it right away