Cream and butter contain pretty much the same substances, so why cream should sour much faster has been a mystery. Both are emulsions—tiny globules (小球體) of one liquid evenly distributed throughout another. The difference lies in what’s in the globules and what’s in the surrounding liquid, says Brocklehurst, who led the investigation.

　　In cream, fatty globules drift about in a sea of water. In butter, globules of a watery solution are locked away in a sea of fat. The bacteria which make the food go bad prefer to live in the watery regions of the mixture. “This means that in cream, the bacteria are free to grow throughout the mixture,” he says.

　　When the situation is reversed, the bacteria are locked away in compartments (隔倉室) buried deep in the sea of fat. Trapped in this way, individual colonies cannot spread and rapidly run out of nutrients (養料). They also slowly poison themselves with their waste products. “In butter, you get a self-limiting system which stops the bacteria growing,” says Brocklehurst.

　　The researchers are already working with food companies keen to see if their products can be made resistant to bacterial attack through alterations to the food’s structure. Brocklehurst believes it will be possible to make the emulsions used in salad cream, for instance, more like that in butter. The key will be to do this while keeping the salad cream liquid and not turning it into a solid lump.

　　36. The significance of Brocklehurst’s research is that ________.

　　A) it suggested a way to keep some foods fresh without preservatives

　　B) it discovered tiny globules in both cream and butter

　　C) it revealed the secret of how bacteria multiply in cream and butter

　　D) it found that cream and butter share the same chemical composition

　　37. According to the researchers, cream sours fast than butter because bacteria ________.

　　A) are more evenly distributed in cream

　　B) multiply more easily in cream than in butter

　　C) live on less fat in cream than in butter

　　D) produce less waste in cream than in butter

　　38. According to Brocklehurst, we can keep cream fresh by ________.

　　A) removing its fat

　　B) killing the bacteria

　　C) reducing its water content

　　D) altering its structure

　　39. The word “colonies” (Line 2, Para. 4) refers to ________.

　　A) tiny globules

　　B) watery regions

　　C) bacteria communities

　　D) little compartments

　　40. Commercial application of the research finding will be possible if salad cream can be made resistant to bacterial attack ________.

　　A) by varying its chemical composition

　　B) by turning it into a solid lump

　　C) while keeping its structure unchanged

　　D) while retaining its liquid form

　　36. A 37. B 38. D 39.C 40. D

　　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 (錦標賽) 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.

　　21. 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

　　22. 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

　　23. 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

　　24. 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

　　25. 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.