题材：天文 难度：★★★★★ 字数：434 建议时间：15分钟

　　Astronomers have witnessed the biggest bang since the Big Bang—the moment about 15 billion years ago when the universe was created in a massive explosion.The huge burst of energy from the edge of the universe is estimated to be second only to the moment of creation in its explosive force,releasing more energy in two seconds than the sun will give out in its lifetime.Scientists hope the explosion—known

as a gamma-ray burst because it emits energy in the form of gamma radiation—will shed light on the earliest stages in the evolution of the stars and galaxies.Gamma-ray bursts cannot be seen by the human eye but if they could the sky would light up like a camera flash each time they occurred.They are by far the most energetic events in the universe and,until now,have remained largely a mystery.

　　The latest gamma-ray burst to be detected accurately occurred last December.Using a network of telescopes and satellites,the astronomers were able to calculate its distance from earth at about 15 billion light years.This means it must have happened soon after the Big Bang itself,while the intensity of the radiation revealed it to be the biggest bang recorded by man.Scientists from the American National Aeronautics and Space Administration and the California Institute of Technology are to announce details of their analysis this week.The huge distance between the source of the explosion and the Earth suggests gamma-ray bursts are up to 10 times larger than previously thought,said Jonathan Katz,professor of physics at Washington University in St Louis.

　　“Gamma-ray bursts may be the most distant things we will ever see and as such will act as beacons to probe into the very distant regions of the universe when stars and galaxies were first formed.”

　　American spy satellites looking for the radiation released from Soviet nuclear tests first detected gamma-ray bursts in 1967 but the details were kept classified until 1973.For nearly 25 years scientists were hampered in their efforts to find an explanation for the huge explosions because they lasted no longer than a few seconds.The inability to explain them led to speculation that gamma-ray bursts were the remnants of nuclear battles between alien civilizations,or even the exhaust energy of extraterrestrial spaceships going into warp drive.Two satellites,the American Compton gamma-ray observatory and the Italian-Dutch Bepposax satellite,have now been able to locate the precise direction of gamma-ray bursts within seconds of them occurring.John Quenby,professor of physics at Imperial College of Science,Technology and Medicine in London,said the most likely explanation for gamma-ray bursts is that they result from the enormous energy released when two very dense objects—called neutron stars—collide.

　　1-According to the passage,“the Big Bang” is used to express all of the following EXCEPT

　　［A］ the huge energy burst which created the universe.

　　［B］ the energy burst which took place in the center of the universe.

　　［C］ the explosion which took place in the form of gamma radiation.

　　［D］ the explosion which happened about 15 billion years ago.

　　2-According to the passage gamma-ray bursts

　　［A］ were detected accidentally.

　　［B］ were first detected by Soviet nuclear experts.

　　［C］ were made known to the public after 1973.

　　［D］ were soon given clear and detailed explanation.

　　3-It can be concluded from the passage that the study of the Big Bang will probably

　　［A］ lead to the discovery of earliest human civilizations .

　　［B］ tell how and when the universe was formed .

　　［C］ display the intensity of nuclear radiation .

　　［D］ make it possible to communicate with other civilizations .

　　4-Which of the following is NOT directly stated but can be inferred from the passage?

　　［A］ Gamma-ray explosion is very,very far away from the earth.

　　［B］ Scientists believe that the universe was formed out of the Big Bang.

　　［C］ Gamma-ray bursts lasted only a very short period of time.

　　［D］ Scientists are still working hard to find more plausible explanations for the Big Bang.

　　5-Which of the following can be used as the best title of the passage?

　　［A］ Gamma-ray bursts and nuclear wars between alien civilizations.

　　［B］ Astronomy and the creation of universe.

　　［C］ Big Bang theory explains the mystery of universe.

　　［D］ Big BangⅡ sheds light on evolution of universe.