问题 填空题

一只理想变压器的原线圈接在220V交变电压上,将一根导线在铁芯上绕一圈后接上一只电压表时,电压表的示数为0.25V,将导线取走,换上一只副线圈时,副线圈所接的"36V 4W"的灯泡正好正常发光,则此副线圈的匝数是____匝,通过原线圈的电流是____A。

答案

144  1/55A

题目分析:将一根导线在铁芯上绕一圈后接上一只电压表时,电压表的示数为0.25V,可得,解得变压器原线圈上的匝数为880,换上一只副线圈时,副线圈所接的"36V 4W"的灯泡正好正常发光则有:,解得 ,根据可得通过原线圈的电流是1/55A

点评:做本题的关键是正确掌握公式

阅读理解

“It was cool,because I got a chance to be in a studio and see how a record is made,”says 14-year-old Javon Martin,who joined the music clubhouse 3 years ago.“It has impacted my life in a big way. People are actually starting to see me as an artist.”Ten-year-old Akheylah Hunter didn’t play an instrument when she became a club member last year. Now,she plays piano and sings with the band. What she likes best,she says,is performing.“We performed in different places,”she says.“We go on trips and it is fun.”

Since the Music Clubhouse opened three years ago,it’s served almost 500 kids.Aggeler says performing in front of different audiences helps the young musicians build self-esteem.Coming to the club to prepare for those performances helps them learn how to deal with their personal problems and concerns.

“I can see what it does for them and it just develops confidence,”he explains.“It’s also an escape from the big problems we have in the neighborhood. So whether they feel embarrassed about a zit on their face,or they feel embarrassed because they’re not as tall as somebody,they can rap about it and let it out a little bit.”

To expand the club and help more kids learn music,Aggeler sought the support of the community. The Berklee College of Music and local music stores have provided free equipment. The club has also gotten support from the Music and Youth Initiative,a nonprofit that develops after school music education programs in underserved communities in Massachusetts. All these have made it possible to provide kids who may not have the means to get private music lessons the opportunity to still learn music and get all the benefits that music education brings.”

小题1:Why does the writer mention the two children in the first paragraph?

A.To tell readers that all children like music.

B.To provide examples of how children like the club.

C.To convince readers that music can solve many problems.

D.To show readers how to discover children’s potentials.小题2:Which of the following was NOT mentioned as a benefit of joining the club?

A.Helping the youngsters to build self-confidence.

B.Helping its members escape from problems.

C.Learning to deal with personal problems.

D.Learning to get help from nonprofit groups.小题3:What is Mr.Aggeler’s possible post?

A.An organizer of the club.

B.A conductor of the band.

C.An expert in child problems.

D.A parent of one of the children.小题4:What does the writer intend the passage to be?

A.An advertisement for a club.

B.A promotion of some non-profit groups.

C.An introduction of a music club for children.

D.A try to call for attention on children’s needs.小题5:Which of the following might NOT be included in activities of the club?

A.Putting on performances.

B.Making records.

C.Traveling to different places.

D.Giving private music lessons.

阅读理解与欣赏

阅读下面文段,回答问题。

  这一天,他和那条船之间的距离缩短了三英里;第二天.又缩短了两英里——因为现在他是跟比尔先前一样地在爬;到了第五天末尾,他发现那条船离开他仍然有七英里,而他每天连一英里也爬不到了。晚秋的晴朗天气仍然继续,他于是继续爬,继续晕,辗转不停地爬;而那头狼也始终跟在他后面,不断地咳嗽和喘气。他的膝盖已经和他的脚一样鲜血淋漓,尽管他撕下了身上的衬衫来垫膝盖,他背后的苔藓和岩石上仍然留下了一路血迹。有一次,他回头看见病狼正饿得发慌地舐着他的血迹,他清清楚楚地看到了自己可能遭到的结局——除非——除非他干掉这只狼。于是,一幕从来没有演出过的残酷的求生悲剧就开始了——病人一路爬着,病狼一路跛着,两个生灵就这样在荒原里拖着垂死的躯壳,相互猎取着对方的生命。

  如果这是一条健康的狼,那么,他觉得倒也没有多大关系;可是,一想到自己要喂到这么一只令人作呕、只剩下一口气的狼的胃里,他就觉得非常厌恶。他就是这样吹毛求疵。现在,他脑子里又开始胡思乱想,又给幻像弄得迷迷糊糊,而神智清楚的时候也愈来愈少,也愈来愈短。

  有一次,他在昏迷中给一个贴着他耳朵喘气的声音惊醒了。只见那只狼一跛一跛地往回跳。它因为身体虚弱,一失足摔了一跤。样子可笑极了,可是他一点也不觉得有趣。他甚至也不害怕。他已经虚弱到了极点,无力害怕了。不过,这一会,他的头脑却很清醒,于是他躺在那儿,细细地想。那条船离他不过四英里路,他把眼睛擦净之后,可以很清楚地看到它;同时,他还看见一条在光辉的大海里破浪前进的小船的白帆。可是,无论如何他也爬不完这四英里路。这一点,他是知道的,而且知道以后,他还非常镇静。他知道他连半英里路也爬不了。不过,他仍然要活下去。在经过了千辛万苦之后,他居然还会死掉,那未免太不合理了。命运对他实在太苛刻了。然而,尽管奄奄一息,他还是不情愿死。也许,这种想法完全是发疯,不过,就是到了死神的铁掌里,他仍然要反抗它,不肯死。

1.试用简洁的语言概括选文内容。

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2.开头为什么反复交代“他和那条船”的距离?

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3.狼的“样子可笑极了”,为什么“他一点也不觉得有趣”?

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4.“这一点,……非常镇静”,“这一点”指什么?

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5.你有过极度疲倦的感受吗?试用你自己的语言描绘出来。

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