2013年英语四级阅读试题及答案6

　　Passage Four

　　Why does cream go bad faster than butter? Some researchers think they the answer，and it comes down to the structure of the food，not its chemical composition - a finding that could help rid some processed foods of chemical preservatives.C ream 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)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 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 (密封仓) buried deep in the sea of fat.Trapped in this way，individual colonies cannot spread and rapidly run out of nutrients.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

　　[答案及分析]：[A]文章第一段破折号后说明了这位科学家的研究意义在于;能够帮助在加工一些食品过程去除化学防腐剂。

　　37. According to the researchers.cream sours faster than butter because bacteria_____ .

　　A) are more evenly distributed in cream

　　B) multiply more easily in cream than is butter

　　C) live on less fat in cream than in butter

　　D) produce less waste in cream than in butter

　　[答案及分析]：[B]文章第二段具体阐明了奶酪和牛油在结构上的区别。在段尾这位科学家说：“这就意味着奶酪里细菌能够在整个混合物里更自由的生长。”

　　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

　　[答案及分析]：[D]文章一开头就指出奶酪和牛油化学成份相同，奶酪更易变质是在于它们结构上的区别。而这位科学家的研究是通过改变奶酪的结构保持它的新鲜。

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

　　A) tiny globules B) watery regions

　　C) bacteria communities D) little compartments

　　[答案及分析]：[C]在这篇文章里。colonies的意思是“细菌群”。

　　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

　　[答案及分析]：[D]本文最后一段补充说，把这项研究发现用于商业，关键在于如何使奶酪在保鲜的同时保持液体状态，而不凝结成固体。