（一） Black Hole请根据短文内容，回答问题。Most scientists agree that black holes exist bu

共享题干题 （一） Black Hole请根据短文内容，回答问题。 Most scientists agree that black holes exist but are nearly impossible to locate. A black hole in the universe is not a solid object, like a planet, but it is shaped like a sphere (球体). Astronomers(天文学家) think that at the center of a black hole there is a single point in space with infinite (无限的 ) density ( 稠密 ) . This single point is called a singularity ( 奇点). If the singularity theory is correct, it means that when a massive star collapses, all the material in it disappears into the singularity. The center of a black hole would not really be a hole at all, but an infinitely dense point. Anything that crosses the black hole is pulled in by its great gravity. Although black holes do exist, they are difficult to observe. These are the reasons. No light or anything else comes out of black holes. As a result, they are invisible to a telescope. In astronomical terms, black holes are truly. For example, a black hole formed by the collapse of a giant star would have an event horizon (视界) only 18 miles across.The nearest black holes would be dozens of light years away from Earth. One light year is about 6 trillion (万亿) miles. Even the most powerful telescopes could not pick out an object so small at such a great distance. In 1994 the Hubble Space Telescope provided evidence that black holes exist. There are still answers to be found, however, so black holes remain one of the mysteries of the universe.1.[不定向选择题]Black holes exist but are difficult to observe.A.Right B.Wrong C.Not mentionedABC确定 2.[不定向选择题]The attraction of two large stars leads to gravity.A.Right B.Wrong C.Not mentionedABC确定

1.参考答案：A
参考解析：黑洞是存在的，但是不容易被观察到。题干中的关键词为difficult，用它回到原文定位，在首句能找到difficult的近义词impossible。首句的意思是黑洞确实存在，但很难定位(locate)，与题意信息相符，故选A。
2.参考答案：C
参考解析：两颗大星体的相互吸引产生重力。用数字two和中心词9ravity(吸引力)回到原文定位，文章并没有相关信息。故选择C。3.[不定向选择题]The nearest black holes are hundreds of light years away from us.A.Right B.Wrong C.Not mentionedABC确定

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