【文章內(nèi)容簡介】 to the structure of the food, not its chemical position—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 partments (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(yǎng)料). They also slowly poison themselves with their waste products. “In butter, you get a selflimiting system which stops the bacteria growing,” says Brocklehurst. The researchers are already working with food panies 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.1. 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 position答案：A2. 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答案：B3. 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：D4. The word “colonies” (Line 2, Para. 4) refers to __________. A) tiny globules B) watery regions C) bacteria munities D) little partments答案：C5. Commercial application of the research finding will be possible if salad cream can be made resistant to bacterial attack _____________. A) by varying its chemical position B) by turning it into a solid lump C) while keeping its structure unchanged D) while retaining its liquid form答案：D資料2： Humanity uses a little less than half the water available worldwide. Yet occurrences of shortages and droughts（干旱）are causing famine and distress in some areas, and industrial and agricultural byproducts are polluting water supplies. Since the world’ population is expected to double in the next 50 years, many experts think we are on the edge of a widespread water crisis. But that doesn’t have to be the oute. Water shortages do not have to trouble the world — if we start valuing water more than we have in the past. Just as we began to appreciate petroleum more after the 1970s oil crises, today we must start looking at water from a fresh economic perspective. We can no longer afford to consider water a virtually free resource of which we can use as much as we like in any way we want. Instead, for all uses except the domestic demand of the poor, governments should price water to reflect its actual value. This means charging a fee for the water itself as well as for the supply costs. Governments should also protect this resource by providing water in more economically and environmentally sound ways. For example. often the cheapest way to provide irrigation（灌溉）water in the dry tropics is through smallscale projects, such as gathering rainfall in depressions（凹地）and pumping it to nearby cropland. No matter what steps governments take to provide water more efficiently, they must change their institutional and legal approaches to water sue. Rather than spread control among hundreds or even thousands of local, regional, and national agencies that watch various aspects of water use, countries should set up central authorities to coordinate water policy.6. What is the real cause of the potential water crisis? A) The world population is increasing faster and faster. B) Half of the worl