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我将能确定一定会发生或者一定不会发生的事件叫做____

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确定事件

同类题2

阅读下文,回答问题。

飞向深空的跳板

      ①美国总统奥巴马就任以后就计划在21世纪30年代中期之前将宇航员送上火星乃至更遥远的宇宙空间,将小行星作为人类飞向火星的跳板。不久的将来,小行星有望成为飞向太阳系其它行星理想的中转站。

      ②太阳系除了八大行星之外,还有数量众多的小行星,现已发现的小行星有几十万颗,它们的轨道绝大多数处于火星轨道和木星轨道之间,但也有少数小行星的轨道很特殊,甚至与地球的轨道很接近。我们要去的小行星,就是这些轨道非常接近地球轨道的小行星,它们被称作近地小行星。

      ③科学家指出,如果直接访问火星那样表面重力很大的星球,必须耗费大量的燃料降落和更多的燃料再次起飞。因为所有的燃料都必须从地球带去,这需要极其昂贵的花费。如果改去很小的小行星,那里的表面重力也许只有地球的百万分之一,可以比较缓慢地接近目标,徐徐地着陆。而当任务完成,要飞离这颗小行星,几乎不用花费什么力气。

      ④小行星在太空中甚至可以用来作为“跳板”。在某些小行星上很多岩石中含有结晶水,它们可以通过研磨岩石和加热粉尘来提取。水对于生命的维持是至关重要的,可以利用太阳能电池板发出的电力,将其分解成氢气和氧气,从而转化为燃料。通过这样在途中添加燃料,将使行星际飞行更容易实现。

      ⑤小行星不仅可以作为进一步飞往火星的跳板,它们本身也极具研究价值。它们拥有尚未改变的最古老的物质,这些物质将会告诉我们太阳系的早期是什么状态。研究人员通过研究陨石和分析光谱发现,有一些小行星是金属组成的,有一些是石质的,还有一些富含碳甚至存在复杂的有机化合物。

      ⑥面对数量众多的小行星,我们应该选择哪一颗作为我们的目的地呢?近地小行星的公转速度与地球相差很小,因此会慢慢靠拢地球,并慢慢离地球而去。这样的轨道便于从地球飞去的航天器登陆。科学家发现,近地天体中个头小的小行星远比个头大的小行星更常见。因此,我们很可能首先考虑登录一些很小的小行星。

      ⑦可是,登陆小行星并非轻而易举。这些很小的小行星都是超快自转的天体,把一块石头放在它表面,石头将会自行飞起来并飞离这颗小行星。因此要把人和飞船系留在那里十分困难。事实上,一个比足球场还小的小行星不仅自转可能很快,而且又可能是一颗松散的尘埃球,比地球上的任何物体都更脆弱。

      ⑧飞船飘入深空中,这是登陆小行星面临的最主要的危险,还有小的卫星石块的袭击,另外位于表面的细尘,一旦受到扰动就容易扬起来,成为一团云,数日不散,遮住视线,钻进航天服的接合处和机械中,妨碍设备正常工作。

      ⑨现在,载人飞往小行星所需要的硬件已经在计划中,根据预测,第一批小行星探测者也许会在2020年后的某个时候出发。

同类题5

任务型阅读

Common public speaking problems

    The use of “I feel”, “I think” and “maybe”

    In the question-and-answer session of the speaking competition, many contestants began their answers with uncertain expressions like “I feel”, “I guess”, “I hear”, “maybe” and “perhaps”. These words show that the person is only speaking from his or her point of view____

    Work on keeping your answers brief and to the point____ Instead of the empty-sounding “I guess”, using facts, together with a clear conclusion based on those facts, is far more likely to be popular with an audience.

Using only one speaking style

    “Don't stick to the same tone____ For example, when they spoke about their dreams some sounded romatic. Others used humor. Very few used several different styles together. Try mixing more than one style, rather than just sticking with the same one.

    Irresponsible answers

    Public speaking is different from personal conversations. You're responsible for your words____So you should think twice before you talk. Don't belike the student who, when asked about his opinion on book piracy(盗版), started by saying he supported it.

    Talking around the topic rather than directly answering it

    You should focus on one point and give a clear solution. The key is to work out what question is being asked. Is it asking you to discuss a certain topic or to present your own point of view?

    Use one or two arguments together and give a strong conclusion____

A. It can be boring. Try to mix it up.

B. Also work on delivering them with calmness and confidence.

C. Even though you want to answer quickly, you don't want to sound foolish.

D. This lacks the support of facts and seems not to be reliable for the judges and audience.

E. Remember that judges are not judging you on whether they agree, but on your ability to say what you think clearly.

F. Confidence is extremely important in public speaking as it lets a speaker sound more convincing.

G. Deliberate gestures and affected(做作的)expressions of feelings are improper in a successful speech.