English grammar, beloved by sticklers, is feared by non-native speakers of English. Many of its idiosyncrasies can turn into traps even for the most confident speakers. But some of the most binding rules in English are things that native speakers know but don't know they know, even though they use them every day. When someone points one out, it's like a magical little shock. According to a book by Mark Forsyth, "adjectives absolutely have to be in this order: opinion-size-age-shape-color-origin-material-purpose noun. So you can have a lovely little old rectangular green French silver whittling knife. But if you mess with that order in the slightest you'll sound like a maniac." Mixing up the above phrase does, as Forsyth writes, feel inexplicably wrong (a rectangular silver French old little lovely whittling green knife), though nobody can say why. It's almost like secret knowledge we all share. Learn the language in a non-English-speaking country, however, and such "secrets" are taught in meticulous detail. Many English grammar textbooks that are regularly used to teach English to non-native speakers usually lay out the adjective order in the same way as Forsyth's surprising illumination. Non-native speakers learning English work very hard over the rule, committing it to memory and thinking through the order when called upon to describe something using more than one adjective. The fact is, a lot of English grammar rules only come as a surprise to those who know them most intimately. Learning rules doesn't always work, however. Forsyth also takes issue with the rules we think we know, but which don't actually hold true. In a lecture about grammar, he dismantles the commonly held English spelling mantra "I before E except after C." It's used to help people remember how to spell words like "piece" or "receive," but, Forsyth says, there are only 44 words that follow the rule, and 923 that don't. His prime examples? "Their," "being," and "eight."

If you think your oral health is perfect because of your choice of having sugar-free products then you are highly mistaken, warn dental health experts. Sugar-free drinks and foods are as damaging to teeth as the ones that contain sugar. Researchers at the Oral Health Cooperative Research Center (Oral Health CRC) reached this startling revelation after testing as many as 23 different types of sugar-free drinks, including soft drinks. These drinks were found to have acidic additives and low pH levels, which are harmful to tooth enamel. The researchers said that we all know sugar is not good for our teeth, but not many know that drinks that are acidic, whether or not they contain sugar, can also be bad for our teeth. The presence of sugar leads to tooth decay by forming plaque on the tooth surface and converting to acid. The acid in turn attacks teeth by dissolving the tooth enamel's outer layer. Therefore, acidic drinks can erode teeth in the same way. "Many people are not aware that while reducing your sugar intake does reduce your risk of dental decay, the chemical mix of acids in some foods and drinks can cause the equally damaging condition of dental erosion," affirmed Professor Eric Reynolds. Firstly, the acid will dissolve the tooth enamel's surface and has the potential to reach the level where it can expose the soft pulp inside the tooth. There are many sugar-free alternatives available on the market but Professor Reynolds and colleagues have clearly mentioned in their research paper that many sugar-free products remain harmful to teeth owing to their chemical composition. The researchers have gone through the studies in the Oral Health CRC in which dental enamel softening and tooth surface loss was measured after teeth were exposed to different drinks. Most of the drinks led to the softening of dental enamel. No significant difference was found between sugary and non-sugary drinks when it came to which causes more loss of tooth enamel. The Academy of General Dentistry said that the worst time to drink a high-acid beverage is when one is thirsty because that is when the mouth's saliva levels are at their lowest. Saliva helps neutralize acids. The Oral Health CRC has suggested labels that have detailed information should be present on sugar-free products so consumers can assess them with regard to their tooth health. Regular checkups with a dentist can help detect dental erosion at an early stage. "In light of its studies, the Oral Health CRC is of the view that current product testing and labeling regulations for foods and drinks are not sufficient to enable consumers to make informed choices in order to avoid the risk of dental erosion," concluded Professor Reynolds and colleagues.

Language and thought are quite closely related. Language helps us to represent thought explicitly in our minds. It helps us reason, plan, remember, and communicate. Communication with others gets most of the press when people talk about language. But could it be that the language we use actually causes us to think in certain ways? Could the language we speak make our internal representations of ideas different from those of people who speak a different language? It's true that different languages phrase things differently. But does that mean it is possible to have thoughts in one language that can't be translated into another? Unfortunately most of the people who answer "yes" to this question turn out to have nothing in mind other than single basic word meanings. It is pretty easy to find words in one language that don't have exact single-word equivalents in another. Schadenfreude in German is a famous example. It refers to a kind of malicious pleasure some people find in other people's misfortunes. But does the lack of an exact single-word English equivalent mean that English speakers aren't able to experience that feeling themselves or recognize it in others? Surely not. I believe I just explained in English what Schadenfreude means. Another familiar example concerns color. Some languages have far fewer words than English for naming fairly basic colors. While some (like Greek and Russian) have more than one basic word for shades of blue, quite a few others use the same word for both "green" and "blue." Some languages have hardly any color-name words. Does this mean their speakers can't physically distinguish multiple colors? Apparently not. An experiment in the 1960s found that members of a New Guinea tribe (the Dani) whose language named only two colors were just as good at matching a full spectrum of color chips as English speakers. And lest we forget, I'd better mention the tired old claim that the Yup'ik and Inuit peoples (of arctic Siberia, Alaska, Canada, and Greenland) see the world differently because they have some huge number of words for different varieties of snow. You may be disappointed to learn that there's hardly any truth to the linguistic claim: the family of eight languages of these peoples have only a modest number of snow terms. Four were mentioned in a 1911 description of a Canadian language by the great anthropologist Franz Boas: a general word for snow on the ground; and words roughly corresponding to "snowflake," "blizzard," and "(snow)drift." That was it. Boas was making a point that had nothing to do with numbers of words or their influence on thinking. It was about the way different languages draw slightly different distinctions when naming things. But years of exaggeration and embellishment led to a seductive myth that people with no knowledge of the languages of the Yup'ik and Inuit peoples repeat over and over in magazines and newspapers. They report with wonder that the Yup'ik and Inuit peoples have some amazing number of words for snow, a number that differs wildly from writer to writer: some say dozens or scores while others say hundreds or thousands. They offer no evidence, and they usually ignore the fact that English, too, has plenty of words for snow – words like "slush," "sleet," "avalanche," "blizzard," and "flurry."