变压器负载运行时副边电压变化率随着负载电流增加而增加。

题型:判断题

问题:

变压器负载运行时副边电压变化率随着负载电流增加而增加。

考点:电气工程公共基础第三节电动机与变压器第三节电动机与变压器题库
题型:判断题

足球也能发电(10分)

①2012年欧洲杯大幕落下之际,正是发电足球在南非的学校操场上腾空而起之时。课余时间尽兴踢足球,天黑了抱着足球点灯看书。这并非天方夜详,而是一些非洲少年的现实生活。他们踢的那个足球并非是传说中的阿拉丁神灯,而是美国几名大学生发明的可以发电的足球。

②发电足球的发明者是美国哈佛大学4名女生,她们认为这项发明可以帮助偏僻地区的人们在夜晚照明。目前,利用运动的能量发电的发明越来越多,其基本原理都是差不多的,就是把运动时的部分动能转化为电能。当杰西卡·马修斯提出足球发电的设想后,她的3名好友也十分赞同。大家一起查找资料,并利用零花钱购买一些材料在业余时间进行研制。

③女生们利用感应线圈发电技术,把金属线圈、磁铁和蓄电池安装在足球内。当足球无论是在脚下滚动还是腾空飞行时,线圈都会在球中不停地转动发电,所产生的电能被储存在蓄电池内。说起来容易做起来难,要让发电机正常工作,要合理安排发电线圈与磁铁的位置,并让发电装置无论足球怎么剧烈运动都不会脱落而乱晃。这花费了女生们不少心思,才让发电线圈固定在一个合适的角度上。

④这款足球由12块六边形的弹性泡沫面板组成,耐用性强,95%的材料都能回收重复利用,且防水防潮,无论是刮风还是下雨,都照样发电。在足球的表面有一个隐形的插座,类似于耳机接口。这个插座安装在一个哑铃形揭盖下,可以为LED灯、手机、MP3 等小电器提供电能。

⑤目前,这款足球已经在南非一些学校进行了实验,效果还不错。一群少年按照通常的方法玩了半个小时足球,结果让一盏10瓦的LED灯亮了 3小时。可见,学生们下午的足球运动完全可以为晚上的学习提供照明。由于安装在足球内的发电装置很轻,额外增加的质量约为150克,不会影响正常的足球运动.少年们拿到这款足球后只是注意到隐藏在一块皮面上的插座,没有感觉它比其他球重,玩起来感觉也和其他球没有什么差异。

⑥哈佛女生的足球发电创意甚至引起了美国前总统克林顿的关注,他评价说:“面对电力资源紧缺的问題,这是一种另辟蹊径的解决办法,它能给缺电地区的人们带来电能,改善人们的生活质量。”其实,发电足球除了能给缺电地区送去光明外,也是户外活动和野外探险的好工具,一场激烈的足球赛之后,夜晚的帐蓬就可以靠它照明了。(选自《知识就是力量》2012年第09期)

小题1:下列对选文第②、③、④段的主要内容概况正确的是( )(3分)

A.第②段:基本原理。第③段:研制发电足球。第④段:发电足球的构成。

B.第②段:提出设想。第③段:研制发电足球。第④段:发电足球的构成。

C.第②段:基本原理。第③段:研制发电足球。第④段:发电足球的构成及性能。

D.第②段:提出设想。第③段:研制发电足球。第④段:发电足球的构成及性能。小题2:下列说法不符合原文意思的一项是( )(3分)

A.利用运动的能量发电的基本原理都是把运动时的部分动能转化为电能。

B.合理安排发电线圈与磁铁的位置并让发电线圈固定在一个合适的角度操作起来很难。

C.发电足球除了能给缺电地区送去光明,也是户外活动和野外探险的好工具。

D.这种面对电力资源紧缺的问题,另辟蹊径的解决办法,启发我们要善于思考,敢于创新,有服务社会的意识。小题3:“知识就是力量”,请根据文意,设想一下如何制作能发电的篮球。(4分)

题型:判断题

如果直线y=ax+b经过点(1,3),那么a+b=______.

题型:判断题

有一成片荒地需要估价。获知该成片荒地的面积为4km2。适宜进行"五通一平"的开发后分块有偿转让;可转让土地面积的比率为50%;附近地区与之位置相当的小块"五通一平"熟地的单价为1000元/m2,开发期需要3年;将该成片荒地开发成"五通一平"熟地的开发成本、管理费用等估计为2.5亿元/km2;贷款年利率为10%;投资利润率为20%;当地土地转让中卖方需要缴纳的税费为转让价格的5%,买方需要缴纳的税费为转让价格的4%。估算该成片荒地的总价和单价。

题型:判断题

根据我国现行建筑安装工程费用构成的相关规定,下列费用中,属于安装工程费用的是()。

A、设备基础、工作台的砌筑工程费或金属结构工程费用

B、房屋建筑工程供水、供暖等设备费用

C、对系统设备进行系统联运无负荷运转工作的调试费

D、对整个生产线负荷联合试运转所发生的费用

题型:判断题

阅读理解。

     He's an old cobbler (修鞋匠) with a shop in the Marais, a historic area in Paris. When I took him my

shoes, he at first told me: "I haven't time. Take them to the other fellow on the main street ; he'll fix them

for you right away."

     But I'd had my eye on his shop for a long time. Just looking at his bench loaded with tools and pieces

of leather, I knew he was a skilled craftsman (手艺人). "No," I replied, "the other fellow can't do it well."

     "The other fellow" was one of those shopkeepers who fix shoes and make keys"while-U-wait"-without

knowing much about mending shoes or making keys. They work carelessly, and when they have finished

sewing back a sandal strap (鞋带) you might as well just throw away the pair.

     My man saw I wouldn't give in, and he smiled. He wiped his hands on his blue apron ( 围裙), looked

at my shoes, had me write my name on one shoe with a piece of chalk and said,"Come back in a week."

     I was about to leave when he took a pair of soft leather boots off a shelf.

     "See what I can do?"  he said with pride. "Only three of us in Paris can do this kind of work."

     When I got back out into the street, the world seemed brand-new to me. He was something out of an

ancient legend, this old craftsman with his way of speaking familiarly, his very strange, dusty felt hat, his

funny accent from who-knows-where and, above all, his pride in his craft.

     These are times when nothing is important but the bottom line, when you can do things any old way

as long as it"pays", when, in short, people look on work as a path to ever-increasing consumption (消费)

rather than a way to realize their own abilities. In such a period it is a rare comfort to find a cobbler who

gets his greatest satisfaction from pride in a job well done.

1. Which of the following is true about the old cobbler ?

A. He was equipped with the best repairing tools.

B. He was the only cobbler in the Marais.

C. He was proud of his skills.

D. He was a native Parisian.

2. The sentence "He was something out of an ancient legend." ( paragraph 7 ) implies that _____.

A. nowadays you can hardly find anyone like him

B. it was difficult to communicate with this man

C. the man was very strange

D. the man was too old

3. According to the author, many people work just to _____.

A. realize their abilities

B. gain happiness

C. make money

D. gain respect

4. This story wants to tell us that _____ .

A. craftsmen make a lot of money

B. whatever you do, do it well

C. craftsmen need self-respect

D. people are born equal

更多题库