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  3. The unknown pervades the universe. That which people can see, with the aid of various sorts of telescope, accounts for just 4% o

The unknown pervades the universe. That which people can see, with the aid of various sorts of telescope, accounts for just 4% o

admin2011-02-25  51
问题     The unknown pervades the universe. That which people can see, with the aid of various sorts of telescope, accounts for just 4% of the total mass. The rest, however, must exist. Without it, galaxies would not survive and the universe would not be gently expanding, as witnessed by astronomers. What exactly constitutes this dark matter and dark energy remains mysterious, but physicists have recently uncovered some more clues, about the former, at least.
    One possible explanation for dark matter is a group of subatomic particles called neutrinos. Neutrinos are thought to be the most abundant particles in the universe. According to the Standard Model, the most successful description of particle physics to date, neutrinos come in three varieties, called "flavors". Again, according to the Standard Model, they are point-like, electrically neutral and massless. But in recent years, this view has been challenged, as physicists realized that neutrinos might have mass.
    The first strong evidence came in 1998, when researchers at an experiment, based in Japan, showed that muon neutrinos produced by cosmic rays hitting the upper atmosphere had gone missing by the time they should have reached an underground detector. Its operators suspect that the missing muon neutrinos had changed flavor, becoming electron neutrinos or-more likely-tau neutrinos. Theo- ry suggests that this process, called oscillation, can happen only if neutrinos have mass.
    Over the coming months and years, researchers hope to produce the most accurate measurements yet. The researchers created a beam of muon neutrinos first. On the other side of the target sat a particle detector that monitored the number of muon neutrinos leaving. The neutrinos then travelled 750km (450 miles) through the Earth to a detector in a former iron mine in Soudan, Minnesota. Researchers then were able to confirm that a significant number of muon neutrinos had disappeared-that is, they had changed flavor. While their mass is so small that neutrinos cannot be the sole constituent of dark matter, they have an advantage in that they are at least known to exist.
    The same cannot be said for sure of another possible form of dark matter being studied by a group of physicists in Italy. If the result continues to withstand scrutiny, it would appear to be evidence for an exotic new sort of fundamental particle, known as an axion, which could also be a type of dark matter.
Which one of the following is NOT true about the experiment mentioned in Paragraph 4 ?
选项 A、It can be used to confirm previous suspects about neutrinos.
B、The number of muon neutrinos changed in the process of the experiment.
C、A more accurate number can be put on the mass of neutrinos based on this experiment.
D、The result of the experiment contradicts that in 1998.
答案D
解析 细节题；首先需要判断的是第四段的实验和第三段的实验之间的关系，通过过渡句researchers hope to produce the most accurate measurements yet以及比较两段内容之后，我们才可以最终确定，这里提到的两个实验在方向上是一致的，都是在论证：neutrinos确实会出现flavor的转变，而这一段的进步就体现在它更加精确地确定了发生转变的数量，所以A选项的confirm准确地描述了这种关系，而D选项的contradict则是错误的表述。而B和C的表述是对原文中对实验过程的细节捕述的同义表达，在比较阅读中判断其准确性难度不大，所以对此实验描述出现错误的是D选项。
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