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6、After almost 30 years of arguing that a black hole swallows up everything that falls into it, British astrophysicist (天體物理學(xué)家) Stephen Hawking moved backward last week.

The world-famous writer of "Brief History of Time" said he and other scientists had got it wrong. "I've been thinking about this problem for the last 30 years, and I think I now have the answer to it," said Hawking. "A black hole only appears to form but later opens up and set free information about what fell inside. So we can be sure of the past and can predict the future." The findings could help solve the "black hole information paradox（似是而非的觀點(diǎn)）", an important puzzle in modern physics.

A black hole is an area in space where matter is under such pressure that even light can not escape from its gravitational pull(引力). But, exactly what happens there has long puzzled scientists.

Black holes occur when a powerful star burns up its nuclear fuel and gravity forces it to break down in on itself. The great weight of the star's outer layers moves in towards its center. The force of gravity keeps nearly all light from escaping and nothing inside can be seen from the outside. The star actually disappears from the universe into a point of infinite density（高密度）. That is a place where the laws of general relativity that govern space and time break down.

Hawking has devoted most of his life to studying these questions.

At the beginning, cosmologists believed the holes were like a "universal vacuum (真空) cleaner", sucking up everything in their path.

Hawking revolutionized the study of black holes when he proved, in 1976 that, under the strange rules of quantum physics（量子物理）, when black holes form they send out energy and lose mass in the process.

In thinking up this so-called "Hawking radiation", the Cambridge mathematician also created one of the biggest puzzles in physics.

These particles (粒子), he said, contained no information about what has been occurring inside the black hole, or how it formed. Under his theory, once the black hole disappears, all the information within it is lost.

72. What's the importance of Hawking's new findings?

A. They could help solve the puzzle about black holes.

B. They has solved the mystery of "black holes".

C. We can now know what is going on inside "black holes".

D. Scientists have already predicted the future of "black holes" now.

73. What's the meaning of the underlined word "cosmologist" (in Paragraph 9)?

A. A person who studies the universe and its origin and development.

B. A person who studies the stars and their development.

C. A person who travels in a spacecraft.]

D. A person who studies the position of the stars and the movements of the planets.

74. Which of the following is TRUE?

A. Hawking has now studied black holes for more than 40 years.

B. During the course of the black hole's forming the enormous weight of the star's center moves into the outer layers.

C. Almost nothing can escape from the gravitational pull of the black hole.

D. Scientists have been thinking the black hole contains no information.

75. What would be the best title for the passage?

A. The Formation of the Black Hole              B. Black Hole Information Paradox

C. Black Hole Mystery                                 D. The Cause of the Black Hole