听力文摘：探寻无糖可乐的奥秘

Here’s an at-home experiment you can try.

你可以在家做这样的实验。

Take a can of “classic” Coca-Cola and a can of Diet Coke, and without opening either one submerge them in water. A deep sink or a bucket will do the trick. You’ll find the can of Diet Coke rises to the top, while the Classic Coke stays sunk. Can you guess why?

把没打开过的两听可乐（含糖，无糖）放在深槽或者高桶中，里面的水淹没两听可乐，你会发现无糖可乐浮在水面；而含糖可乐却沉下去了。你能猜到原因吗？

The answer lies in the chemical contents of the Diet Coke — in fact, in the very distinction that makes it “Diet”. Although their ingredients are otherwise similar, Diet Coke is not made with real sugar: instead, the makers¹ of Coca-Cola products have replaced the sugar with a synthetic² chemical called Aspartame.

奥秘就在于无糖可乐的成分，这也是“无糖”的原因。虽然，无糖可乐和普通可乐的成分很相似，无糖可乐中添加的并非真正的糖，而是一种做“阿斯巴甜”的合成化学物。

Aspartame, which is commonly known as Nutrasweet, is a kind of substitute sugar — intended to mimic³ the distinctive⁴ taste of sugar without carrying the associated calories.

“阿斯巴甜”是一种常见的代糖甜味剂，不含糖的热量却有糖的甜味。

High Molecular⁵ Density⁶

高分子密度

Real sugar has a high molecular density. In other words you can think of sugar molecules⁷ as being thickly packed together.

真正的糖分子密度高，也就是说糖分子紧密地排列在一起。

This also means sugar molecules themselves will be relatively⁸ heavy, even when dissolved in solution. In the case of the sinking Coke, the real sugar content is acting⁹ as an anchor for the can.

即使溶解在溶液中，相同体积的糖更重。实验中沉下去的普通可乐，正是因为糖成分像锚般让罐子下沉。

Coca-Cola Taste

可乐的味道

There’s also the fact that Nutrasweet is much sweeter than sugar, and so less is needed per can to achieve that recognizable Coca-Cola taste. Thus the bobbing Diet Coke not only has a lower average density, it also has a lower mass — there’s less “stuff” dissolved in the mixture. If you were an advertising¹⁰ executive, you might want to market diet sodas¹¹ as “Light” — it wouldn’t be far from the truth.

代糖比糖甜，所以更少的代糖能达到普通可乐的甜味。这样水中摇摆的无糖可乐不仅平均密度更低，质量也比普通可乐轻——因为更少的代糖溶解在可乐中。如果你是广告商，你可以这样宣传——无糖碳酸饮料的优点：轻。这可没有说大话。

1 makers   

n.制造者，制造商（maker的复数形式）

参考例句：

• The makers of the product assured us that there had been no sacrifice of quality. 这一产品的制造商向我们保证说他们没有牺牲质量。
• The makers are about to launch out a new product. 制造商们马上要生产一种新产品。 来自《简明英汉词典》

2 synthetic   

adj.合成的，人工的；综合的；n.人工制品

参考例句：

• We felt the salesman's synthetic friendliness.我们感觉到那位销售员的虚情假意。
• It's a synthetic diamond.这是人造钻石。

3 mimic   

v.模仿，戏弄；n.模仿他人言行的人

参考例句：

• A parrot can mimic a person's voice.鹦鹉能学人的声音。
• He used to mimic speech peculiarities of another.他过去总是模仿别人讲话的特点。

4 distinctive   

adj.特别的，有特色的，与众不同的

参考例句：

• She has a very distinctive way of walking.她走路的样子与别人很不相同。
• This bird has several distinctive features.这个鸟具有几种突出的特征。

5 molecular   

adj.分子的；克分子的

参考例句：

• The research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。
• For the pressure to become zero, molecular bombardment must cease.当压强趋近于零时，分子的碰撞就停止了。

6 density   

n.密集，密度，浓度

参考例句：

• The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
• The region has a very high population density.该地区的人口密度很高。

7 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

8 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

9 acting   

n.演戏，行为，假装；adj.代理的，临时的，演出用的

参考例句：

• Ignore her,she's just acting.别理她，她只是假装的。
• During the seventies,her acting career was in eclipse.在七十年代，她的表演生涯黯然失色。

10 advertising   

n.广告业；广告活动 a.广告的；广告业务的

参考例句：

• Can you give me any advice on getting into advertising? 你能指点我如何涉足广告业吗?
• The advertising campaign is aimed primarily at young people. 这个广告宣传运动主要是针对年轻人的。

11 sodas   

n.苏打( soda的名词复数 )；碱；苏打水；汽水

参考例句：

• There are plenty of sodas in the refrigerator. 冰箱里有很多碳酸饮料。 来自辞典例句
• Two whisky and sodas, please. 请来两杯威士忌苏打。 来自辞典例句