问题 填空题

瓦斯局部积聚是指大于()立方米的空间内瓦斯浓度达到()时为瓦斯局部积聚。

答案

参考答案:0.5 2.5%

阅读理解与欣赏

汶川大地震成因探寻

  目前,中国正全力进行汶川地震救援,而科学家也开始给这场破坏性如此巨大、影响地区如此广泛的地震寻找成因。

  科学家们称,目前来看,是很多因素的综合作用导致了这次破坏性巨大的地震。

  四川省位于印度板块和欧亚板块两个大陆板块的交界处附近,特别容易发生地震。5000万年前,印度板块在与欧亚板块碰撞之前是个岛屿;目前印度板块在以每年两英寸的速度向北推移──对板块漂移来说,这是个不慢的速度。

  这种快速运动意味着在大陆板块的边缘部位积聚了较大的能量,进而引发能量的剧烈释放,也就是地震。据美国地质调查局(U.S. Geological Survey)称,如此强度的地震每50到100年会发生一次。

  不仅如此,日本筑波大学(Tsukuba University)研究员Yuji Yagi牵头的一个地震研究小组表示,汶川地震可能是沿着断层线分两个不同阶段爆发的,这种情况非常罕见。可能因此而导致地震强度增大、时间延长。

  该研究小组称,第一阶段是沿着龙门山断层线的运动,造成23英尺宽的地壳断裂,约为时50秒。随后不久,沿着该断层线的另外一个部分很可能发生了持续60秒的小滑移。

  Yagi说,这就意味着这个地区经历了为时大约两分钟的强烈地震。与此相比,造成6,000多人死亡的1995年日本神户发生的强烈地震只有20秒,能量也不足汶川地震的1/30。

  其他科学家还指出,汶川地震震源离地表较近,只有6英里。震源浅的地震造成的破坏性更大,因为能量的释放距离地面更近,引发的震动更剧烈。

  不仅如此,由于中国所在大陆板块年代已久,很多地区地壳都很脆,且构造相似。东京大学(Tokyo University)地震研究所的Teruyuki Kato说,这样,地震形成的冲击波能传播数百英里,而能量却没有明显衰减,就像光波在光纤里传播一样。离震中约1,000英里远的上海都有震感。

  与此同时,在距离震中较近的地区,由于长江在四川盆地形成了厚厚的沉积层,地质结构不稳定,震动更为严重。研究者表示,不牢固的地层使地震的破坏力增大;而且土壤肥沃的四川盆地人口密集,增大了人员伤亡的数量。

  当然,有些问题还未找到答案。科学家们表示,该地区的地震研究也因为频繁的塌方而受阻,塌方掩埋了很多地质构造证据,比如地表的裂纹或暴露的山脊。

  Kato说,我们需要进行更多的研究来找到确切成因。不过很清楚的一点是,我们正在研究的是个地震相当活跃的地区。(选自《华尔街日报》中文网络版2008年5月15日)

1、下列说法中,不属于汶川地震破坏性巨大的原因的一项是 [ ]

A、四川省位于印度板块和欧亚板块两个大陆板块的交界处附近,易发地震。

B、汶川地震可能是沿着龙门山断层线分两个阶段爆发,震动时间长。

C、汶川地震属浅源地震,能量释放距离地面近,引发的震动更剧烈。

D、长江在四川盆地形成了厚厚的沉积层,不牢固的地层使地震破坏力增大。

2、下列说法不符合原文意思的一项是 [ ]

A、目前印度板块以每年两英寸的速度向北快速运动,在大陆板块边缘部位积聚的能量剧烈释放,形成地震。

B、美国地质调查局的专家认为,类似于汶川地震这种强度的大地震每50年到100年就会发生一次。

C、此次地震,距震中1000英里远的上海都有震感是因为地震形成的冲击波在传播过程中能量没有明显衰减。

D、地表的裂纹或暴露的山脊等掩埋了很多地质构造证据,从而使得各国专家对汶川地震的研究一再受阻。

3、根据原文提供的信息,下列推断正确的一项是[ ]

A、专家一旦找到汶川地震的确切成因,就能从根本上解决这一带的地震问题。

B、地震持续时间的长短和能量的大小与地震中伤亡人数的多少成正比。

C、1995年神户地震造成的人员伤亡远小于汶川地震,是因为震源离地表远。

D、板块是不断运动的,位于两大板块交界处附近的地区,往往是地震多发地区。

阅读理解

阅读理解。

     There is no denying that students should learn something about how computers work, just

as we expect them at least to understand that the internal-combustion engine (内燃机) has

something to do with burning fuel, expanding gases and pistons (活塞) being driven. For

people should have some basic idea of how the things that they use do what they do. Further,

students might be helped by a course that considers the computer's impact on society. But

that is not what is meant by computer literacy. For computer literacy is not a form of literacy

(读写能力); it is a trade skill that should not be taught as a liberal art.

      Learning how to use a computer and learning how to program one are two distinct

activities. A case might be made that the competent citizens of tomorrow should free

 themselves from their fear of computers. But this is quite different from saying that all ought

to know how to program one. Leave that to people who have chosen programming as a

career. While programming can be lots of fun, and while our society needs some people

who are experts at it, the same is true of auto repair and violin-making.

Learning how to use a computer is not that difficu1t, and it gets easier all the time as

programs become more "user-friendly". Let us assume that in the future everyone is

going to have to know how to use a computer to be a competent citizen. What does the

phrase "learning to use a computer" mean? It sounds like "learning to drive a car", that is,

it sounds as if there is some set of definite skills that, once acquired, enable one to use a

computer.

     In fact, "learning to use a computer" is much more like "learning to play a game", but

learning the rules of one game may not he1p you play a second game, whose rules may

not be the same. There is no such a thing as teaching someone how to use a computer.

One can only teach people to use this or that program and generally that is easily accomplished.

1. To be the competent citizens of tomorrow, people should.

A. try to lay a solid foundation in computer science

B. be aware of how the things that they use do what they do

C. learn to use a computer by acquiring a certain set of skills

D. understand that programming a computer is more essential than repairing a car.

2. In the second paragraph "violin-making" is mentioned to show that .

A. programming a computer is as interesting as making a violin

B. our society needs experts in different fields

C. violin-making requires as much skill as computer programming

D. people who can use a computer don't necessarily have to know computer programming

3. Learning to use a computer is getting easier all the time because .

A. programs are becoming 1ess complicated

B. programs are designed to be convenient to users

C. programming is becoming easier and easier

D. programs are becoming readily available to computer users

4. According to the author, the phrase "learning to use a computer" in Para. 3means learning.

A. a set of rules

B. the fundamentals of computer science

C. specific programs

D. general principles of programming

5. The author's purpose in writing this passage is .

A. to stress the impact of the computer on society

B. to explain the concept of computer literacy

C. to illustrate the requirements for being competent citizens of tomorrow

D. to emphasize that computer programming is an interesting and challenging job.