题目

若圆的半径为3,圆心与点关于点对称,则圆的标准方程为         . 答案:The disaster at the Chernobyl(former USSR前苏联) power station happened quickly and without warning. It was in the early hours of April 26, 1986 when the cooling system of the reactor(反应堆) failed. Minutes later, a violent (猛烈地) explosion blew the top off the reactor and blasted(爆炸生成) a huge cloud of radioactive gas high into atmosphere. Two people were killed immediately. Hundreds received powerful radiation overdose (过量). And more than 25,000 had to be taken away from their homes. Days later, the radioactive cloud had spread as far as Scotland. Its radiation was weak, but all over Europe radioactive rain was falling. In some areas people were advised not to eat fresh vegetables, or drink fresh milk, and the sale of meat was forbidden. The accident at Chernobyl was the world’s worst nuclear accident. In Britain, it convinced (使……相信) many people that all nuclear power stations should be shut down for good. But the Central Electricity Generating Board didn’t agree. They claimed that ·similar disasters could not happen in Britain because of safer designs, fewer deaths are caused using nuclear fuel (燃料) than by mining for coal or drilling for oil and gas. Nuclear accidents are unusually fewer compared with other types of accidents-such as air crashes, fires or dam break-down more nuclear power stations are necessary because the world’s supplies of oil, coal and natural gas are running out. In 1957 in Cumbria (Britain) a nuclear reactor overheated and caught fire. No one was killed but fourteen workers received radiation overdose. Small amounts of gas and dust were let out over the local countryside. An official report said the accident was nearly a full-scale disaster. The Nuclear Authority wanted the report published but the Prime Minister at the time refused. He thought that it would make people less confident in Britain’s nuclear industry. Thirty years later, the cabinet(内阁) records of 1957 were published. Only then did the public discover what had really happened in Cumbria. 1.. One result of the Chernobyl nuclear disaster was that ______. A. 25,000 people were killed                      B. fresh foods were polluted C. people in Scotland were taken away from their homes D. hundreds of houses in Chernobyl were destroyed 2..According to the passage, nuclear accidents______. A. are most unlikely to cause death            B. are always kept secret from the public C. can only happen in underdeveloped countries D. may happen in any country that has nuclear power station. 3.. After the nuclear accident at Chernobyl many people in Britain _______. A. still believed it could not happen in their country. B. were not convinced that nuclear power stations could be safe C. accepted that there would be fewer deaths than in drilling for oil D. supported nuclear power stations because world fuel supplies were low 4... The British Government refused to publish the report on the Cumbria accident because _______. A. Britain’s supplies of oil, coal and gas were running out B. it takes thirty years for the effects of radiation to appear C. fewer people died in that accident than in other types of accidents D. it was concerned that the British people would doubt their country’s nuclear expertise (核技术)
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