[填空题]There might be a massive black hole at the center of our galaxy______(swallow)up stars at a very rapid rate．

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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 tiny. For example, a black h
A. Right
B. Wrong
C. Not mentioned

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Black Holes
What is a black hole Well, it’s difficult to answer this question, since the terms we normally use to describe a scientific phenomenon are inadequate here, Astronomers and scientists think that a black hole is a region of space (not a thing) into which matter has fallen and from which nothing can escape—not even light. So we can’t see a black hole. A black hole exerts (施加) a strong gravitational (重力的) pull and yet it has no matter. It is only space—or so we think. How can this happen
The theory is that some stars explode when their density increases to a particular point; they "collapse" and sometimes a supernova (超新星) occurs. The collapse of a star may produce a "White Dwarf (白矮星) "or a "neutron star"—a star whose matter is so dense that it continually shrinks by the force of its own gravity. But if the star is very large this process of shrinking may be so intense that a black hole re
A. The structure of a star.
B. A collision between two stars.
C. The attraction of two large stars.
D. The shrinking of a large star by its own gravitational force.