大学英语四级阅读专项训练及答案
Why does cram go bad faster than butter? Some researchers think they have 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. 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 小球体 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 隔仓室 buried deep in the sea of fat. Trapped in this way, individual colonies cannot spread and rapidly run out of
nutrients 养料. 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
Amtrak 美国铁路客运公司 was experiencing a downswing in ridership 客运量 along the lines comprising its rail system. Of major concern to Amtrak and its
advertising agency DDB Needham, were the
long-distance western routes where ridership had been declining
significantly.] At one time, trains were the only practical way to cross the vast areas of the west. Trains were fast, very
luxurious, and quite convenient compared to other forms of
transportation existing at the time. However, times change and the automobile became America’s standard of convenience. Also, air
travel had easily established itself as the fastest method of traveling great distances. Therefore, the task for DDB Needham was to encourage consumers to consider other aspects of train travel
in order to change their attitudes and increase the likelihood that trains would be considered for travel in the west.
Two portions of the total market were targeted: 1 anxious fliers—those concerned with safety, relaxation, and cleanliness and 2 travel-lovers—those viewing themselves as relaxed, casual,
and interested in the travel experience as part of their vacation. The agency then developed a campaign that focused on travel experiences such as freedom, escape, relaxation, and enjoyment of
the great western outdoors. It stressed experiences gained by using the trains and portrayed western train trips as wonderful adventures.
Advertisements showed pictures of the beautiful scenery that could be enjoyed along some of the more famous western routes and emphasized the romantic names of some of these trains Empire
Builder, etc.. These ads were strategically placed among family-oriented TV shows and programs involving nature and America in order to most effectively reach target audiences. Results were impressive. The Empire Builder, which was focused on in one ad, enjoyed a
15 percent increase in profits on its Chicago to Seattle route. 31. What’s the author’s purpose in writing this passage?
A To show the inability of trains to compete with planes with respect to speed and convenience.
B To stress the influence of the automobile on America’s standard of convenience.
C To emphasize the function of travel agencies in market promotion.
大学英语四级阅读专项训练及答案
