请根据短文内容，回答题。 Black HolesMost scientists agree that black holes exist but are nea

请根据短文内容，回答题。

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.＜br＞

Anything that crosses the black hole is pulled in by its great gravity.＜br＞

Although black holes do exist, they are difficult to observe. These are the reasons.＜br＞

No light or anything else comes out of black holes. As a result, they are invisible to a telescope.＜br＞

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.＜br＞

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.＜br＞

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.＜

Black holes are part of space. 查看材料

A.Right

B.Wrong

C.Not mentioned