【单选题】
在距离保护中为了监视交流电压回路，均装设“电压断线闭锁装置”，当二次电压回路发生短路或断线时,该装置___。
A. 发出断线信号；
B. 发出信号，断开保护电源；
C. 断开保护电源
D. 发出声音报警。
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答案
B
解析
暂无解析
相关试题
【单选题】
断路器失灵保护是___。
A. 一种近后备保护，当故障元件的保护拒动时，可依靠该保护切除故障；
B. 一种远后备保护，当故障元件的断路器拒动时，必须依靠故障元件本身保护的动作信号起动失灵保护以后切除故障点；
C. 一种近后备保护，当故障元件的断路器拒动时，可依靠该保护隔离故障点；
D. 一种远后备保护，当故障元件的保护拒动时，可依靠该保护切除故障。
【单选题】
停运发电机___之前，应确认励磁调节器已经转移到另外的互感器，并退出发变组B套保护屏可能因失电会造成误动的保护。
A. 1PT；
B. 2PT；
C. 3PT；
D. 中性点变压器。
【单选题】
停运发电机___之前，应确认励磁调节器已经转移到另外的互感器，并退出发变组A套保护屏可能因失电会造成误动的保护和采用其它监视手段进行监视。
A. 1PT；
B. 2PT；
C. 3PT；
D. 中性点变压器。
【单选题】
汽轮发电机运行中出现励磁电流增大，功率因数增高，定子电流随之增大，电压降低，机组产生振动现象，这是由于___。
A. 转子绕组发生两点接地；
B. 转子绕组发生一点接地；
C. 转子不平衡；
D. 系统发生故障。
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Of the following, is considered Herman Melville’s masterpiece.
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【单选题】
Of the following, is NOT Nathaniel Hawthorne’s work.
A. A. The Scarlet Letter
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is regarded as “the father of American literature”.
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Of the following writers, are from the Colonial and Revolutionary Periods.
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B. B. Edgar Ellen Poe & Jonathan Edwards
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The National Day of the United States falls on .
A. A. June 4th
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Of the following, is NOT among the three major radio and TV networks in America.
A. A. the National Broadcasting System (NBS)
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is sold especially to the upper or upper-middle class and it has a reputation for its serious attitude and great bulk.
A. A. The Washington Post
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Of the following universities, has NOT cultivated any American President yet.
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To get a bachelor’s degree, all undergraduate students are required to do the following except .
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Of the following, is NOT the responsibility of the board of trustees in U. S. institutions.
A. A. choosing the president
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Of the following, are NOT among the categories of American higher education.
A. A. universities and colleges
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Higher education in the United States began with the founding of
A. A. Yale University
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Of the following subjects, are NOT offered to elementary school students.
A. A. mathematics and languages
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Formal education in the United States consists of , secondary and higher education.
A. A. kindergarten
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is not one of the three giants in American automobile industry.
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A. A. Agribusinesses reflect the big, corporate nature of many farm enterprises.
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D. D. Agribusinesses include a variety of farm businesses and structures.
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About of American crops are for export.
A. A. half
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The first National Bank of the United States was established with the urge of .
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Chartered companies were NOT granted the by the British King or Queen.
A. A. political authority
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The modern American economy progressed from to , and eventually, to .
A. A. colonial economy, handcraft economy, industrial economy
B. B. farming economy, handcraft economy, industrial economy
C. C. colonial economy, farming economy, industrial economy
D. D. handcraft economy, farming economy, industrial economy
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America produces a major portion of the world’s products in the following fields except .
A. A. machinery
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The President is directly voted into office by .
A. A. all citizens of America
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The Supreme Court is composed of justices.
A. A. six
B. B. seven
C. C. eight
D. D. nine
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The terms for a Senator and Representative are and years respectively.
A. A. two, four
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C. C. two, six
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According to the Constitution, a candidate for President must be .
A. A. at least 35 years old
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The following except are all powers of the President.
A. A. vetoing any bills passed by Congress
B. B. appointing federal judges when vacancies occur
C. C. making laws
D. D. issuing executive orders
【单选题】
All the following except cannot make legislative proposal.
A. A. the Senator
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C. C. the Secretary of State
D. D. the President
【单选题】
The following except are guaranteed in the Bill of Rights.
A. A. freedom of religion
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C. C. freedom of speech and of press
D. D. the right to own one’s weapon if one wishes
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The Bill of Rights .
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D. D. has no relationship with the Constitution
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The Constitution of the United States .
A. A. gives the most power to Congress
B. B. gives the most power to the President
C. C. tries to give each branch enough power to balance the others
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The U. S. Constitution came into effect in .
A. A. 1787
B. B. 1789
C. C. 1791
D. D. 1793
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The Vietnam War was a long-time suffering for Americans, and it continued throughout the terms of Presidents .
A. A. Johnson, Nixon and Ford
B. B. Truman, Eisenhower and Kennedy
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President applied New Deal to deal with the problems of the Great Depression.
A. A. Wilson
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D. D. Kennedy
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The policy of the United States was at the beginning of the two world wars.
A. A. neutrality
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Abraham Lincoln issued to grant freedom to all slaves.
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In May 1775, was held in Philadelphia and began to assume the functions of a national government.
A. A. the First Continental Congress
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The first shots of the American dependence were fired in .
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B. B. Lexington
C. C. Philadelphia
D. D. Boston
