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Passage One
Questions 21 to 25 are based on the following passage:
　　Long after the 1998 World Cup was won, disappointed fans were still cursing the disputed refereeing（裁判）decisions that denied victory to their team. A researcher was appointed to study the performance of some top referees.
　　The researcher organized an experimental tournament（锦标赛）involving four youth teams. Each match lasted an hour, divided into three periods of 20 minutes during which different referees were in charge.
　　Observers noted down the referees’ errors, of which there were 61 over the tournament. Converted to a standard match of 90 minutes, each referee made almost 23 mistakes, a remarkably high number.
　　The researcher then studied the videotapes to analyse the matches in detail. Surprisingly, he found that errors were more likely when the referees were close to the incident. When the officials got it right, they were, on average, 17 meters away from the action. The average distance in the case of errors was 12 meters. The research shows the optimum（最佳的）distance is about 20 meters.
　　There also seemed to be an optimum speed. Correct decisions came when the referees were moving at a speed of about 2 meters per second. The average speed for errors was 4 meters per second.
　　If FIFA, football’s international ruling body, wants to improve the standard of refereeing at the next World Cup, it should encourage referees to keep their eyes on the action from a distance, rather than rushing to keep up with the ball, the researcher argues.
　　He also says that FIFA’s insistence that referees should retire at age 45 may be misguided. If keeping up with the action is not so important, their physical condition is less critical.

51. The experiment conducted by the researcher was meant to _______.
　　A) review the decisions of referees at the 1998 World Cup
　　B) analyse the causes of errors made by football referees
　　C) set a standard for football refereeing
　　D) reexamine the rules for football refereeing
52. The number of refereeing errors in the experimental matches was _______.
　　A) slightly above average
　　B) higher than in the 1998 World Cup
　　C) quite unexpected
　　D) as high as in a standard match
53. The findings of the experiment show that _______.
　　A) errors are more likely when a referee keeps close to the ball
　　B) the farther the referee is from the incident, the fewer the errors
　　C) the more slowly the referee runs, the more likely will errors occur
　　D) errors are less likely when a referee stays in one spot
54. The word “officials” (Line 2, Para.4) most probably refers to _______.
　　A) the researchers involved in the experiment
　　B) the inspectors of the football tournament
　　C) the referees of the football tournament
　　D) the observers at the site of the experiment
55. What is one of the possible conclusions of the experiment?
　　A) The ideal retirement age for an experienced football referee is 45.
　　B) Age should not be the chief consideration in choosing a football referee.
　　C) A football referee should be as young and energetic as possible.
　　D) An experienced football referee can do well even when in poor physical condition.