NASA is releasing several images taken by the Hubble Space Telescope, which is the closest yet look at the red planet. Altogethe

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问题     NASA is releasing several images taken by the Hubble Space Telescope, which is the closest yet look at the red planet. Altogether there are four images, which show the entire planet. Each view shows the planet as it completes one quarter of its daily rotation. In these views the north polar cap is turned toward the Earth and is clearly visible at the top of each picture. The images were taken in the middle of the Martian northern summer, when the polar cap was at its smallest size. During this season the sun shines continuously on the polar cap. Previous spacecraft observations have shown that this summertime polar cap is composed of water ice, just like Earth’s polar caps.
    The Hubble Telescope pictures reveal that great changes have occurred on the surface of Mars in the past 20 years. The Martian surface is ever changing. Some regions that were dark 20 years ago are now bright red; some areas that were bright red are now dark. Winds move sand and dust from region to region, often in huge dust storms. Over long timescales many of the larger bright and dark markings remain stable, but smaller details come and go as they are covered and then uncovered by sand and dust.
Which of the following is TRUE about the north polar cap of Mars in summertime?

选项 A、It is at its largest size.
B、It is changing its shape all the time.
C、It is at its smallest size.
D、It is at its windiest time.

答案C

解析 本题的依据信息就是以上几道题的信息。由于文章较短,而题量较多,一般命题的句子密度较为集中。
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