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  3. The space between the stars is filled with matter that interstellar conditions should prevent from coalescing into solid particl

The space between the stars is filled with matter that interstellar conditions should prevent from coalescing into solid particl

admin2020-03-28  100
问题     The space between the stars is filled with matter that interstellar conditions should prevent from coalescing into solid particle. Yet surprisingly tiny frozen particles, referred to as interstellar grains, do develop in these spaces. These grains are formed out of chemical elements that are synthesized during thermonuclear fusion in stars and supernova explosions.
    The study of interstellar grains has been hampered by the inaccessibility of naturally occurring specimens for use in laboratory experiments. To date, the only source of information about interstellar grains is the stellar electromagnetic radiation that reaches the Earth after passing through regions of space containing interstellar grains. By observing the wavelengths scattered and absorbed by the grains scientists have determined that a grain’s internal structure consists of a core composed of silicates (rocklike material) and a mantle composed entirely of organic compounds. It is hypothesized that each grain begins as a silicate “seedling” ejected from a mature star. Continuous physical and chemical evolution then occurs in the mantle formed around the seedling.
Which of the following describe a process that is most similar to the evolution of an interstellar grain, as it is described in the passage?
选项 A、An onion is peeled layer by layer
B、A piece of iron left outdoors is gradually corroded by rust
C、A balloon is inflated by being pumped full of air
D、A piece of wood is gradually carved down to the size of a chocolate
E、A candy is formed by coating a nut with successive layers of chocolate
答案E
解析 根据文章最后三句所描述的星际颗粒的组成，星际颗粒是由一个硅酸盐核心+有机物外壳组成的，与之最类似的是选项B。A项描述的是变小的过程。B项干扰项，从corroded一词可知，该项描述的是一个变小的过程，但是原文的星际颗粒是变大的。C项尽管气球变大了，但是没有核心。D项描述的是变小的过程。
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本试题收录于： GRE VERBAL题库GRE分类
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