题目内容：

    A black hole is created when a large star burns out. Like our sun, stars are unbelievably hot furnaces (熔炉) that burn their own matter as fuel. When most of the fuel is used up, the star begins to die.

The death of a star is not a quiet event. First, there is a huge explosion. As its outer layer is blasted off into space, the dying star shines as brightly as a billion suns.

After the explosion, gravity pulls in what’s left of the star. As the outside of the star sinks toward the center, the star gets smaller and smaller. The material the star is made of becomes tightly packed together. A star is so dense that a teaspoon of matter from it weighs billion of pounds.

The more the star shrinks, the stronger the gravity inside it becomes. Soon the star is very tiny, and the gravity pulling it in is unbelievably strong. In fact, the gravity is so strong that it even pulls light into the star! Since all the light is pulled in, none can flee. The star becomes black when there is no light. Then a black hole is born!

That’s what we know about black holes. What we don’t know is this: What happens inside a black hole after the star has been squeezed into a tiny ball? Does it keep getting smaller and smaller forever? Such a possibility is hard to imagine.

But if the black hole doesn’t keep shrinking, what happens to it? Some scientists think black holes are like doorways to another world. They say that as the star disappears from our universe, it goes into another universe. In other words, a black hole in our universe could turn into a “white hole” in a different universe. As the black hole swallows light, the white hole shines brightly — somewhere else. But where? A different place, perhaps, or a different time — many years in the past or future.

Could you travel through a black hole? Right now, no. Nothing we know of could go into a black hole without being crushed. So far the time being, black holes must remain a mystery.

Black holes are a mystery — but that hasn’t stopped scientists from dreaming about them. One scientist suggested that in the future we might make sure of the power of black holes. They would supply all of Earth’s energy needs, with plenty to spare. Another scientist wondered if a black hole could someday be used to swallow earthly waste — a sort of huge waste disposal in the sky!

1.What do we know about stars in the universe?

A.When a star begins to die, there’s no fuel left in it.

B.After the explosion, a star gets as small as a teaspoon.

C.A star explodes when it dies and then becomes smaller and smaller.

D.A star gets smaller and smaller because the outer layer of a star sinks toward the center.

2.Which of the following doesn’t help produce a black hole?

A.The dying star shines very brightly. B.The light can’t go out of the star.

C.The gravity inside the star is very strong. D.The star becomes very tiny and dense.

3.What can we know from the passage?

A.A star will blast and die when it lacks fuel to support its burning.

B.Man can never travel through a black hole but can make use of its power.

C.A black hole can swallow everything because it becomes smaller all the time.

D.Scientists have found that a black hole goes into another universe and becomes a white hole.

4.What is the best title for the passage?

A.A New Scientific Discovery: Black Holes B.How Do Black Holes Come into Being?

C.What Are Black Holes? D.Travel Through A Black Hole