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D次列车的运行充分发挥了铁路运输量大、速度快的优势。下列关于D次列车的描述，科学合理的解释是[ ]

A．“车速是55m／s”，这意味着行驶500m运行时间为13s

B．“紧急刹车后要冲出近3km才能停住”，这说明物体具有惯性

C．“为了安全起见，铁路两旁2m以内不允许站人”，这是因为气体流速大的地方压强小

D．“D次列车车体质量仅8.5t，全车采用铝合金材料制成”，这是利用了铝合金材料高强度、低密度的特点

答案

BCD

选择题

2012年7月1日，我省开始试行居民生活用电阶梯电价。此前省物价局为此专门举行听证会，并表示听证方案将结合本省实情，未能亲临听证会现场的社会各界人士可以继续通过信件提出自己的看法。从政治生活角度看，这一做法

A．有利于扩大公民的民主权利

B．实现了公民对国家权力的直接行使

C．体现了政府为人民服务，对人民负责

D．坚持了一切从实际出发，实事求是
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问答题

It is hard to predict how science is going to turn out, and if it is really good science it is impossible to predict. If the things to be found are actually new, they are by definition unknown in advance. You cannot make choices in this matter. (46)You either have science or you don’t, and if you have it you are obliged to accept the surprising and disturbing pieces of information, along with the neat and promptly useful bits.

The only solid piece of scientific troth about which I feel totally confident is that we are profoundly ignorant about nature. Indeed, I regard this as the major discovery of the past hundred years of biology. It is, in its way, an illuminating piece of news. (47)It would have amazed the brightest minds of the 18th century Enlightenment to be told by any of us how little we know and how bewildering the way ahead seems. (48)It is this sudden confrontation with the depth and scope of ignorance that represents the most significant contribution of the 20th century science to the human intellect. In earlier times, we either pretended to understand how things worked or ignored the problem, or simply made up stories to fill the gaps. Now that we have begun exploring in earnest, we are getting glimpses of how huge the questions are, and how far from being answered. Because of this, we are depressed. (49)It is not so bad being ignorant if you are totally ignorant; the hard thing is knowing in some detail the reality of ignorance, the worst spots and here and there the not-so-bad sports, but not true light at the end of the tunnel nor even any tunnels that can yet be trusted.

But we are making a beginning and there ought to be some satisfaction. There are probably no questions we can think up that can’t be answered, sooner or later, including even the matter of consciousness. (50)To be sure, there may well be questions we can’t think up, ever, and therefore limits to the reach of human intellect, but that is another matter. Within our limits, we should be able to work our way through to all our answers if we keep at it long enough, and pay attention.

(47)It would have amazed the brightest minds of the 18th century Enlightenment to be told by any of us how little we know and how bewildering the way ahead seems.
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