单项选择题

发电机能承受的过载能力与过载时间有关，当发电机过载为1.4倍额定定子电流时，允许的过电流时间应为（取整数）（ ）。

A.9s
B.19s
C.39s
D.28s
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多项选择题
在电力工程中低压配电装置的电击防护措施中，下列哪些间接接触防护措施是正确的？（ ）
A.采用Ⅱ类设备
B.设置不接地的等电位联结
C.TN系统中供给380V移动式电气设备末端线路，间接接触防护电器切断故障回路最长时间不宜大于0.4s
D.TN系统中配电线路采用过电流保护电器兼作间接接触防护电器时，当其动作特性不满足要求，应采用剩余电流动作保护电器
未分类题
SectionBDirections: There are 2 passages in this section. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A），B),C) and D). You should decide on the best choice and mark the corresponding letter on Answer Sheet 2 with a single line through the centrE.Passage OneQuestions 52 t0 56 are based-on the following passagE.Headlines have bannered the sad news about American education for years: Johnny Cant Read ; Johnny Cant Count ; Johnny Cant Write ...Are youngsters in other industrialized countries doing any better? Yes, in many ways they are, and theres one big reason: they work harD.The consequences are sobering. Students in the U.S. now enter the job market with inferior skills. Once the unquestioned champion in industrial research, America is watching its lead dwindlE.Some experts go so far as to suggest that failings in education put the nation in danger of becoming a second-class economic power. Whether or not thats the case is a key element in a bubbling debate over intemational competitiveness. Consider just these few examples of how American students are falling behind:When Japanese teenagers finish the 12th grade, they have the equivalent of three to four more years of school than U.S. high school graduates do. Stanfords Thomas Rohlen, a leading expert on Japan, says half of them know as much as the average U.S. college graduates.Nine of 10 Japanese get high school diplomas. But nearly a quarter of Americas teenagers drop out sending one million untrained youngsters into the job market eveU year. The problem would be worse, some experts say with a straight face; if so many teenagers didnt stay in school they could take drivers education and get a driver’s licensE.For years, foreigners have outclassed young Americans in academic knowledge, and this week sees still another indictment (谴责 ) of U.S. education: new details on how thousands of 12th graders in selected countries did on a 1982 algebra test given by the Intemational Association for Evaluation of Educational Achievement. Chinas Hong Kong ranked first, barely ahead of Japan. The U.S. finished 14th among the 15 countries and areas, and ahead of ThailanD.and behind Hungary. In a United Nations survey of what students in nine countries know about foreign cultures, the U.S. comes in next to last. One test of American 12-year-olds shows 20 percent unable to locate even their own nation on a world map. Our students lag behind, and it doesnt bode (预示 ) well for our country, says Herbert Walberg, a comparative education expert for the University of Illinois in Chicago. Fifty-five percent of Americas jobs involve information processing. If we dont have good, solid skills in language, geography, math and science, weII be at a severe disadvantagE. 52.American newspapers have carried the sad news about American education that _ .A.Johnny cant read or writeB.many Amencan students cant find a jobC.American youngsters do not work hardD.many American young people are illiterates
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F.S.
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