we know that a wide range in taste acuity exists，and this variation is as normal as variations in eye and hair color.
“Some people，called supertasters，describe bitter compounds as being extremely bitter，while others. called nontasters，find these same bitter compounds to be tasteless or only weakly bitter，\bitter compounds is one of many ways to identify biological difterences in food preference because supertasting7 is not limited to bitterness. (476) 词汇：
publicize v.引起公众对?的注意;(用广告)宣传 ferment v.(使)发酵 geneticist n.遗传学家
dietary adj.饮食的;规定食物的 acuity n.敏锐;尖锐 注释：
1.Penn State College of Agricultural Sciences：即Penn State University-College of Agricultural Sciences宾州州立大学农学院。Penn是Pennsylvania的缩写，是美国宾夕法尼亚州州名。宾州州立大学建于1855年，在全国共有24个分校。在句中，Penn State College of Agricultural Sciences用作定语，修饰food scientist。
2.well-publicized efforts to reduce the salt content in food：大力宣传减少食物含盐量的做法
3.1eft many people struggling to accept fare that simply does not taste as good to them as it does to others：使得许多人努力去接受适合其他人而不适合他们口味的食物。fare相当于food。 4.1ead investigator：研发项目负责人
5.?carefully screened participants who sampled salty foods as soup and chips，on multiple occasion，spread out over weeks：??经过仔细筛选的实验参与者，他们在几周内的不同时间里品尝了汤和薯条等含盐食物。 6.too pronounced：此处pronounced为形容词，意为very noticeable，conspicuous(明显的，显著的)。 7.supertasting：超重味感 练习：
1.In paragraph 2，John Hayes points out that A.it is good to health to eat food without salt. B.many people reject low-salt food completely.
C.many people accept low-salt tasteless food reluctantly D.food with reduced salt tastes better. 2.The fourth paragraph describes briefly
A.how to select subjects and what to do in the research. B.how to identify supertasters and nontasters. C.why to limit the number of subjects to 87 persons. D.why to select more male subjects than female ones. 3.The article argues that supertasters
A.1ike the taste of saltiness to block sweet tastes in food. . B.1ike snack foods as saltiness is their primary flavor. C.consume less salt because they don t like intensive tastes. D.1ike to share salty cheese with nontasters.
4.Which of the following applies to supertasters in terms of bitter taste?
A.They like bitterness in foods as well as saltiness. B.They like high-salt cheese as it has intense bitter taste. C.They prefer high-salt cheese，which tastes less bitter. D.They prefer high-salt cheese as it is good to health. 5.What message do the last two paragraphs carry? A.Taste acuity is genetically determined.
B.Taste acuity is developed over time after birth.
C.Taste acuity is related to one’s eye and hair color. D.Taste acuity is still a mysterious subject in science. 答案与题解：
1.C 根据短文的第二段内容，很多人因为食物中的含盐量降低，所以必须做出很大努力(struggling)去适应，而低盐食物对于他们来说，口味很不好(fare that simply does not taste?good to them)。选项C有accept reluctantly(勉强接受)表达了这层意思，所以是正确的选择。A、B、D三个选项均是错误的。 2.A第四段介绍了科学家是如何设计这项研究的，它包含了研究对象的人数、性别、人选条件、咸度味感分级表等。选项A概括了这方面的内容，所以是答案。而选项B、C、D所述内容均不符合该段的意思。
3.B短文的第五段提供了答案。supertaster在这里的意思是：口味重的人，在本文中，nontaster是其反义词，即，口味清谈的人。该段告诉我们，口味重的人消耗更多的盐;因为快餐食品的主要味道就是咸味，而且咸度越高，口味越好，所以口味重的人对快餐较为偏爱。选项B表达了上述内容，所以是答案。 4.C短文第六段提供了答案。该段告诉我们，奶酪发酵会产生苦味，
supertasters不喜欢苦味，而高含盐量可以盖住奶酪里的苦味，这是他们偏爱高盐奶酪的原因。所以，只有C是正确选择。
5.A 文章第七段中，Hayes引用了75年前一位遗传学专家的实验。从这项实验中，Hayes得出的结论是，Taste acuity(味觉敏度)上的差异与他们头发和眼睛的颜色上的差异是同一类
现象，也就是说，都是与生俱来的。第八段又说，这是一种biological difference(生物差异)，所以A是答案。B说味觉敏度是后天形成的，显然与作者的结论相左。C说味觉敏度的差异与头发和眼睛的颜色上的差异有关，显然是错误的。D的内容在最后两段都没有提到，所以不会是答案 第四十六篇
Marvelous Metamaterials
Invisibility cloaks1 would have remained impossible，forever locked in science fiction，had it not been for the development of metamaterials2.In Greek，“meta” means beyond，and metamaterials can do things beyond what we see in the natural world-like shuffle light waves around an object，and then bring them back together3.If scientists ever manage to build a full-fledged invisibility cloak，it will probably be made of metamaterials.
“We are creating materials that don’t exist in nature，and that have a physical phenomenon that doesn't exist in nature，”says engineer Dentcho Genov. “That is the most exciting thing.” Genov designs and builds metamaterials-such as those used in cloaking-at Louisiana Tech University in Ruston，Louisiana4.
An invisibility cloak will probably not be the first major accomplishment to come from the field of metamaterials. Other
applications are just as exciting. In many labs，for example，scientists are working on building a hyperlens. A lens is a device-usually made of glass-that can change the direction of light waves. Lenses are used in microscopes and cameras to focus light，thus allowing a researcher to see small things or a photographer to capture image of things that are far away.
A hyperlens，however，would be made of metamaterials. And since metamaterials can do things with light that ordinary materials can't，the hyperlens would be a powerful tool. A hyperlens would allow
researchers to see things at the smallest scale imaginable-as small as the wavelength of visible light.
Genov points out that the science of metamaterials is driven by the imagination：If someone can mink of an idea for a new behavior for light，then the engineers can find a way to design a device using metamaterials. “We need people who can imagine，”he says.
Since 2006，many laboratories have been exploring other kinds of metamaterials that don't involve just visible light. In fact，scientists are finding that almost any kind of wave may respond to metamaterials. At the Polytechnic University of Valencia in Spain5，Jose
Sanchez-Dehesa is working with acoustics, or the science of sound. Just as an invisibility cloak shuffles waves of light，an “acoustic” cloak would shuffle waves of sound in a way that’s not found in nature. In an orchestra hall，for example. an acoustic cloak could redirect the sound waves-so someone sitting behind a column would hear the same concert as the rest of the audience，without distortion.
Sanchez-Dehesa，an engineer，recently showed that it's possible to build such an acoustic cloak, though he doubts we’ll see one any time soon. “In principle，it is possible，”he says，but it might be impossible to make one，he adds.
Other scientists are looking into ways to use larger metamaterials as shields around islands or oil rigs6 as protection from tsunamis. A
tsunami is a giant, destructive wave. The metamaterial would redirect the tsunami around the rig or island，and the wave would resume its journey on the other side without causing any harm. 词汇：
cloak n.斗篷，披风 hyperlens n.超透镜 metamaterial n.超材料 acoustics n.声学
full-fledged adj.完全成熟的，完全合格的tsunami n.海震，海啸 注释：
1.Invisibility cloaks：隐形衣。在《哈利·波特与死亡圣器》(Harry Potter and the Deathly Hallows)一书中，哈利通过邓布利多的转交继承了他父亲的隐形衣。该书是英国女作家J.K.罗琳创作的哈利·波特系列小说的第7部。 2.?had it not been for the development of metamaterials：??如果超材料尚未得到开发的话。该句使用的是虚拟过去时的倒装结构。虚拟过去时表示与过去事实相反的假设;因为是倒装结构，所以将情态动词had提到主语之前。如使用正常语序，该句可写为....if it had not been for the development of metamaterials.
3.“meta”means beyond, and metamaterials can do things beyond what we see in the natural world-like shuffle light waves around an object，and then bring them back together：“meta\
metamaterials(超材料)能做出我们在自然界看不到的事情，例如将光波移动到某个物体周围，然后将光波全部收回。
4.Louisiana Tech University in Ruston，Louisiana：路易斯安那理工大学，位于路易斯安那州拉斯顿市。该校为公立大学，1894年建校，是美国最为重要的研究型大学之一。
5.the Polytechnic University of Valencia in Spain：瓦伦西亚理工大学，位于西班牙东南部的瓦伦西亚市，该校建于1968年。 6.oil rigs：石油钻塔 练习：
1.What is true for metamaterials?
A.They will always remain in science fiction. B.They are already a reality.