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问题 单项选择题

某火力发电厂主厂房低压厂用电系统为中性点直接接地，设置两台低压厂用变压器，采用动力中心(PC)和电动机控制中心(MCC)供电方式。

若两台变压器为明备用，下述接线方式正确的是( )。

A．两台低压厂用变压器宜手动切换；
B．动力中心和电动机控制中心宜成对设置，电动机控制中心由对应的动力中心单电源供电；
C．Ⅰ类电动机和75kW及以上的Ⅱ、Ⅲ类电动机宜由动力中心供电；
D．对于单台的Ⅰ、Ⅱ类电动机应单独设立电动机控制中心，由不同的动力中心引接的双电源供电，凡接有Ⅰ类负荷，双电源应自动切换。

答案

参考答案：C

解析： 根据DL/T 5153-2002第4.5.1条。

单项选择题

目前，世界经济一体化程度最高的一体化组织是______。

A．欧盟
B．北美自由贸易区
C．东南亚国家联盟
D．亚太经合组织
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填空题

Almost every day we see something in the papers about the latest exciting developments in the space race. Photographs are regularly flashed to the earth from thousands and even millions of miles away. They are printed in our newspapers and shown on our television screens as a visible proof of the man’s newest achievements. The photographs neatly sum up the results of these massive efforts to ’ conquer space’ and at the same time they exposed the absurdity of the undertaking. All we can see is an indistinguishable blob that is supposed to represent a planet seen from several thousand miles away. We are going to end up with a little moon-dust and a few stones which will be put behind glass in some museum. (41)__________
(42)__________It is just an extension of the race for power on earth. Only the wealthiest nations can compete and they do so in the name of pure scientific research. But in reality, all they are interested in is power and prestige. They want to impress us, their spectators, with a magnificent show of strength. Man has played the power game ever since he appeared on earth. Now he is playing it as it has never been played before. The space race is just another aspect of the age-old argument that "might is right".
(43)__________But what has the space race done to relieve the suffering of the earth’s starving millions In what way has it raised the standard of living of any one of us As far as the layman is concerned, the practical results of all this expenditure of money and efforts are negligible. Thanks to space research, we can now see television pictures transmitted live halfway across the globe and the housewife can use non-stick frying pans in the kitchen. The whole thing becomes utterly absurd when you think that no matter what problems man overcomes, it is unlikely that he will ever be able to travel even to the nearest star.
(44)__________For the first time in his history, man has the overwhelming technological resources to combat human suffering, yet he squanders them on meaningless pursuits.
(45)__________Individuals with limited budgets usually get their priorities right; they provide themselves with necessities before trying to obtain luxuries. Why can’t great nations act in the same sensible way Let us put our house in order first and let space look after itself.
[A] An increasing number of people even begin to picture a space travel in recent years.
[B] Poverty, hunger, disease and war are man’s greatest enemies and the world would be an infinitely better place if the powerful nations devoted half as much money and effort to these problems as they do to the space race.
[C] The space race is not simply the objective search for knowledge though it is often made out to be.
[D] On the other hand, people benefit dramatically from the development of science and technology.
[E] This is hardly value for money when you think that our own earth can provide countless sights that are infinitely more exciting and spectacular.
[F] We are often told that technological know-how, acquired in attempting to get us into orbit, will be utilized to make better on earth.
[G] If a man deprived himself and his family of food in order to buy and run a car, we would consider him mad.
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