对于母线差动保护,当各单元电流互感器变比不同时,则应用补偿变流器进行补偿。补偿方式应

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问题:

对于母线差动保护,当各单元电流互感器变比不同时,则应用补偿变流器进行补偿。补偿方式应以变比较大为基准,采用降流方式。

考点:保险经纪人考试低压电工考试低压电工考试题库
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[选修3-3]

(6分)题10图为一种减震垫,上面布满了圆柱状薄膜气泡,每个气泡内 充满体积为V0,压强为P0的气体。当平板状物品平放在气泡上时,气泡被压缩。若气泡内气体可视为理想气体,其温度保持不变。当体积压缩到V时气泡与物品接触面的边界为S。求此时每个气泡内气体对接触面处薄膜的压力。

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7.(13 分)肠道病毒EV71 为单股正链(+RNA)病毒,是引起手足口病的主要病原体之一。下面为该病毒在宿主细胞肠道内增殖的示意图。

  据图回答下列问题:

(2)假定病毒基因组+RNA含有7500个碱基,其中A和U占碱基总数的40%。病毒基因组+RNA 为模板合成一条子代+RNA 的过程共需要碱基G和C________个。

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Several years ago, at the height of the dotcom boom, it was widely assumed that a publishing revolution, in which the printed word would be supplanted by the computer screen, was just around the corner. It wasn’t: for many, there is still little to match the joy of reading a printed book and settling down for one hour. But recently some big technology companies, including Google, Amazon, Microsoft and Yahoo, contend that the dream of bringing books online is still very much alive.

The digitizing of thousands of volumes of print is not without controversy. On Thursday, Google, the world’ s most popular search engine, posted a first installment of books on Google Print. This collaborative effort between Google and several world’s leading research libraries aims to make books available to be searched and read online free of charge. Although the books included so far are not covered by copyright, the plan has attracted the rage of publishers.

Five large book firms are suing Google for violating copyright on material that it has scanned and, although out of print, is still protected by law. Google has said that it will only publish short extracts from material under copyright unless given express permission to publish more, but publishers are unconvinced. Ironically, many publishers are collaborating with Google Print Publisher, which aims to give readers an online taste of books that are commercially available. The searchable collection of extracts and book information is intended to tempt readers to buy the complete books online or in print form.

Amazon, the world’s largest online retailer, has made plans to enter the mass e-book market by selling a vast array of goods. Given that Google should impinge upon its central territory, Amazon revealed that it would introduce two new services. Amazon Pages will allow customers to search for key terms in selected books and then buy and read online whatever part they wish. Amazon Upgrade will give customers online access to books they have already purchased as hard copies. Customers are likely to have to pay five cents a page, with the bulk going to the publisher.

Microsoft has also joined the online-book trend. In October, the software giant said it would spend around $ 200 million to digitize texts, starting with I50,000 that are in the public domain, to avoid legal problems. It will do so in collaboration with the Open Content Alliance. And on Thursday, coincidentally the same day as Google and Amazon announced their initiatives, Microsoft released details of a deal with the British Library, the country’s main reference library, to digitize some 25 million pages ; these will be made available through MSN Book Search, which will be launched next year.

What is the text talking about()

A. The goods of Google

B. The differences between books printed and books online

C. Some big technology companies bring plans on the e-books

D. The publishers don’t agree with the e-books plan

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下面是1650—1850年的世界人口变化(单位:百万)。导致这一时期世界人口变化的主要因素解读错误的是()。

A.欧洲人口的增加得益于工业革命的开展

B.非洲人口的下降与罪恶的黑奴贸易有关

C.城市化进程的加快推动了欧亚人口的增长

D.农耕经济的繁荣促进了亚洲人口的增长

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非法转让、倒卖土地使用权罪

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