Black Holes
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. Black holes are part of space.
A. Right B. Wrong C. Not mentioned
2. Black holes exist but are difficult to observe.
A. Right B. Wrong C. Not mentioned
3. The center of a black hole is empty.
A. Right B. Wrong C. Not mentioned
4. The attraction of two large stars leads to gravity.
A. Right B. Wrong C. Not mentioned
5. The sun is the heaviest star in the universe.
A. Right B. Wrong C. Not mentioned
6. The nearest black holes are hundreds of light years away from us.
A. Right B. Wrong C. Not mentioned
7. The Hubble Space Telescope helps scientists to understand the nature of the universe.
A. Right B. Wrong C. Not mentioned
答案与解析
1. A。题干：黑洞是太空的一部分。利用space回到原文定位，很容易找到文中首段第三句和第二段第一句都有一致的信息。因此选择A。
2. A。题干：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。
3. B。题干：黑洞的中心是空的。用中心词the center来定位，首段倒数第二句有答案：其中心不是一个洞，由此证明中心不是空的，因此选择B。
4. C。题干：两颗大星体的相互吸引产生重力。用数字two和中心词gravity(吸引力)回到原文定位，文章并没有相关信息。故选择C。
5. c。题干：太阳是宇宙最重的星体。用中心词the sun回到原文定位，文章并未提及与太阳相关的信息。因此选择C。
6. B。题干：离我们最近的黑洞有几百光年远。用中心词nearest定位，原文倒数第二段有相关信息。但原文说的是“最近的黑洞离地球有几十光年(dozens)远”，而不是
“hundreds”。因此选择B。
7. A。题干：Hubble太空望远镜帮助人们了解宇宙的本质。由专有名词the Hubble Space Telescope回到原文定位，不难发现相关信息在最后一段。原文信息与题干信息是一致的。
故选A。
